diff --git a/locale/en/pirates.cfg b/locale/en/pirates.cfg
index fdfcd54b..88f1adcf 100644
--- a/locale/en/pirates.cfg
+++ b/locale/en/pirates.cfg
@@ -279,12 +279,12 @@ class_purchase=__1__ bought the class __2__. ([font=scenario-message-dialog]__3_
 class_upgrade=__1__ upgraded their class from __2__ to __3__ ([font=scenario-message-dialog]__4__[/font]).
 
 
-class_take_spare=__1__ took the spare class __2__. ([font=scenario-message-dialog]__3__[/font]) 
-class_give_spare=A spare __1__ class with given to __2__. ([font=scenario-message-dialog]__3__[/font])
-class_give_up=__1__ gave up __2__.
-class_becomes_spare=A __1__ class is now spare.
-class_give_up_error_no_class=Class error: You don't have any class to give up.
-class_revoke=__1__ revoked __2__ from __3__.
+# class_take_spare=__1__ took the spare class __2__. ([font=scenario-message-dialog]__3__[/font]) 
+# class_give_spare=A spare __1__ class with given to __2__. ([font=scenario-message-dialog]__3__[/font])
+# class_give_up=__1__ gave up __2__.
+# class_becomes_spare=A __1__ class is now spare.
+# class_give_up_error_no_class=Class error: You don't have any class to give up.
+# class_revoke=__1__ revoked __2__ from __3__.
 class_purchase_error_prerequisite_class=Class purchase error: You need to be a __1__ to buy this.
 
 roles_confirm_captain=__1__ accepted the role of captain.
@@ -310,8 +310,8 @@ roles_notify_looking_for_captain=Looking for a suitable captain...
 
 warn_nearly_afk_captain=Note: If you go idle as captain for too long, the role passes to another crewmember.
 
-error_class_assign_redundant=Class error: You're already a __1__.
-error_class_assign_unavailable_class=Class error: No spare class of that type is available.
+# error_class_assign_redundant=Class error: You're already a __1__.
+# error_class_assign_unavailable_class=Class error: No spare class of that type is available.
 
 
 
@@ -405,17 +405,17 @@ gui_crew_window_buttons_join_crew=Join Crew
 gui_crew_window_buttons_join_spectators=Spectate
 gui_crew_window_buttons_join_spectators_tooltip=You won't be able to rejoin the crew for a short while after you do this.
 gui_crew_window_crewmembers=Crew Members
-gui_crew_window_crewmembers_give_up_class=Give Up Class
-gui_crew_window_crewmembers_give_up_class_tooltip=Give Up Class
+# gui_crew_window_crewmembers_give_up_class=Give Up Class
+# gui_crew_window_crewmembers_give_up_class_tooltip=Give Up Class
 gui_crew_window_crewmembers_resign_as_officer=Resign as Officer
 gui_crew_window_crewmembers_resign_as_officer_tooltip=Give up the officer role.
 gui_crew_window_spectators=Spectators
 gui_crew_window_vote_for_difficulty=Vote for Difficulty
-gui_crew_window_spare_classes=Spare Classes
-gui_crew_window_assign_class_button=Give class: __1__
-gui_crew_window_assign_class_button_tooltip=Give the selected player the class __1__.\n\n Class description: __2__
-gui_crew_window_selfassign_class_button=Take class: __1__
-gui_crew_window_selfassign_class_button_tooltip=Give yourself the spare class __1__.\n\n Class description: __2__
+# gui_crew_window_spare_classes=Spare Classes
+# gui_crew_window_assign_class_button=Give class: __1__
+# gui_crew_window_assign_class_button_tooltip=Give the selected player the class __1__.\n\n Class description: __2__
+# gui_crew_window_selfassign_class_button=Take class: __1__
+# gui_crew_window_selfassign_class_button_tooltip=Give yourself the spare class __1__.\n\n Class description: __2__
 gui_crew_window_captains_actions=Captain's Actions
 gui_crew_window_captains_actions_disband_crew=Disband Crew
 gui_crew_window_captains_actions_disband_crew_tooltip=End the run. You will be prompted again after clicking.
@@ -431,8 +431,8 @@ gui_crew_window_captains_actions_make_officer=Make Officer
 gui_crew_window_captains_actions_make_officer_tooltip=Make this player an Officer. (or use /officer {player})
 gui_crew_window_captains_actions_unmake_officer=Unmake Officer
 gui_crew_window_captains_actions_unmake_officer_tooltip=Remove this player as an Officer. (or use /officer {player})
-gui_crew_window_captains_actions_revoke_class=Revoke Class
-gui_crew_window_captains_actions_revoke_class_tooltip=Put this player's class back in the Spare Classes pool.
+# gui_crew_window_captains_actions_revoke_class=Revoke Class
+# gui_crew_window_captains_actions_revoke_class_tooltip=Put this player's class back in the Spare Classes pool.
 gui_crew_window_captains_actions_summon_crew=Summon Crew to Ship
 gui_crew_window_captains_actions_summon_crew_tooltip=Teleport crewmembers to the ship.
 gui_crew_window_captains_actions_tax=Tax Crew
@@ -443,6 +443,16 @@ gui_crew_window_crew_age=Age: __1__
 gui_crew_window_crew_capacity_and_difficulty=__1__, Capacity __2__.
 gui_crew_window_crew_count=Crew Members (__1__)
 
+gui_classes=Classes
+gui_classes_available_classes=Available classes
+gui_classes_taken_by=Taken by
+gui_classes_actions=Actions
+gui_classes_take=Take
+gui_classes_drop=Drop
+gui_classes_take_enabled_tooltip=Equip the class to receive bonuses!
+gui_classes_take_disabled_tooltip=This class is currently in use by someone
+gui_classes_drop_tooltip=Unequip the class to allow someone else to take it
+
 gui_evo_tooltip_1=Local Biter Evolution: __1__
 gui_evo_tooltip_2=Leagues: __1__
 gui_evo_tooltip_3=Kraken: __1__
@@ -534,8 +544,13 @@ gui_questframe_nodamage=Island Quest: No Damage\n\nLaunch a rocket without the s
 gui_crew_tooltip_1=Your Crew\n\nPerform crew actions, such as selecting a class if any are available.
 gui_crew_tooltip_2=Your Crew\n\nYou're a free agent, so there's nothing to do here.
 
+gui_classes_tooltip_1=Class panel\n\nShows list of unlocked classes and let's you take them.\nClasses will start to appear in the list as you unlock them.
+gui_classes_tooltip_2=Class panel\n\nYou're a free agent, so there's nothing to do here.
+
 gui_progress_tooltip=Progress: __1__ leagues.\n\nTravel __2__ leagues to win the game.
 
+gui_close_button=Close
+
 cmd_notify_set_max_crews=The maximum number of concurrent crews has been set to __1__.
 
 cmd_error_not_admin=[ERROR] Only admins are allowed to run this command!
diff --git a/maps/pirates/api_events.lua b/maps/pirates/api_events.lua
index 6af213ae..d45fbee3 100644
--- a/maps/pirates/api_events.lua
+++ b/maps/pirates/api_events.lua
@@ -216,7 +216,14 @@ local function damage_to_artillery(event)
 	if not event.cause.name then return end
 
 
-	if (event.cause.name == 'small-biter') or (event.cause.name == 'small-spitter') or (event.cause.name == 'medium-biter') or (event.cause.name == 'medium-spitter') or (event.cause.name == 'big-biter') or (event.cause.name == 'big-spitter') or (event.cause.name == 'behemoth-biter') or (event.cause.name == 'behemoth-spitter') then
+	if (event.cause.name == 'small-biter')
+		or (event.cause.name == 'small-spitter')
+		or (event.cause.name == 'medium-biter')
+		or (event.cause.name == 'medium-spitter')
+		or (event.cause.name == 'big-biter')
+		or (event.cause.name == 'big-spitter')
+		or (event.cause.name == 'behemoth-biter')
+		or (event.cause.name == 'behemoth-spitter') then
 		if event.cause.force.name ~= memory.enemy_force_name then return end
 
 		-- play alert sound for all crew members
@@ -1064,7 +1071,7 @@ local function event_on_entity_died(event)
 	local crew_id = Common.get_id_from_force_name(entity.force.name)
 	Memory.set_working_id(crew_id)
 	local memory = Memory.get_crew_memory()
-	if memory.id == 0 then return end
+	if not Common.is_id_valid(memory.id) then return end
 
 	base_kill_rewards(event)
 
@@ -1228,9 +1235,9 @@ local function event_on_player_joined_game(event)
 	end
 
 	local crew_to_put_back_in = nil
-	for _, mem in pairs(global_memory.crew_memories) do
-		if mem.id and mem.crewstatus and mem.crewstatus == Crew.enum.ADVENTURING and mem.temporarily_logged_off_characters[player.index] then
-			crew_to_put_back_in = mem.id
+	for _, memory in pairs(global_memory.crew_memories) do
+		if Common.is_id_valid(memory.id) and memory.crewstatus and memory.crewstatus == Crew.enum.ADVENTURING and memory.temporarily_logged_off_characters[player.index] then
+			crew_to_put_back_in = memory.id
 			break
 		end
 	end
@@ -1267,9 +1274,17 @@ local function event_on_player_joined_game(event)
 
 		-- Auto-join the oldest crew:
 		local ages = {}
-		for _, mem in pairs(global_memory.crew_memories) do
-			if mem.id and mem.crewstatus and mem.crewstatus == Crew.enum.ADVENTURING and mem.capacity and mem.crewplayerindices and #mem.crewplayerindices < mem.capacity and (not (mem.tempbanned_from_joining_data and mem.tempbanned_from_joining_data[player.index] and game.tick < mem.tempbanned_from_joining_data[player.index] + Common.ban_from_rejoining_crew_ticks)) then
-				ages[#ages+1] = {id = mem.id, age = mem.age, large = (mem.capacity >= Common.minimum_run_capacity_to_enforce_space_for)}
+		for _, memory in pairs(global_memory.crew_memories) do
+			if Common.is_id_valid(memory.id)
+				and memory.crewstatus
+				and memory.crewstatus == Crew.enum.ADVENTURING
+				and memory.capacity
+				and memory.crewplayerindices
+				and #memory.crewplayerindices < memory.capacity
+				and (not (memory.tempbanned_from_joining_data
+					and memory.tempbanned_from_joining_data[player.index]
+					and game.tick < memory.tempbanned_from_joining_data[player.index] + Common.ban_from_rejoining_crew_ticks)) then
+				ages[#ages+1] = {id = memory.id, age = memory.age, large = (memory.capacity >= Common.minimum_run_capacity_to_enforce_space_for)}
 			end
 		end
 		table.sort(
@@ -1570,14 +1585,38 @@ function Public.event_on_chunk_generated(event)
 
 			if (p.x >= -width/2 and p.y >=-height/2 and p.x <= width/2 and p.y <= height/2) then
 
-				terrain_fn{p = Utils.psum{p, {1, terraingen_coordinates_offset}}, true_p = p, true_left_top = chunk_left_top, left_top = Utils.psum{chunk_left_top, {1, terraingen_coordinates_offset}}, noise_generator = noise_generator, static_params = static_params, tiles = tiles, entities = entities, decoratives = decoratives, specials = specials, seed = seed, other_map_generation_data = other_map_generation_data, iconized_generation = false}
+				terrain_fn{
+					p = Utils.psum{p, {1, terraingen_coordinates_offset}},
+					true_p = p,
+					true_left_top = chunk_left_top,
+					left_top = Utils.psum{chunk_left_top, {1, terraingen_coordinates_offset}},
+					noise_generator = noise_generator,
+					static_params = static_params,
+					tiles = tiles,
+					entities = entities,
+					decoratives = decoratives,
+					specials = specials,
+					seed = seed,
+					other_map_generation_data = other_map_generation_data,
+					iconized_generation = false
+				}
 			else
 				tiles[#tiles + 1] = {name = 'out-of-map', position = Utils.psum{p, {1, terraingen_coordinates_offset}}}
 			end
 		end
 	end
 
-	chunk_structures_fn{true_left_top = chunk_left_top, left_top = Utils.psum{chunk_left_top, {1, terraingen_coordinates_offset}}, noise_generator = noise_generator, static_params = static_params, specials = specials, entities = entities, seed = seed, other_map_generation_data = other_map_generation_data, biter_base_density_scale = Balance.biter_base_density_scale()}
+	chunk_structures_fn{
+		true_left_top = chunk_left_top,
+		left_top = Utils.psum{chunk_left_top, {1, terraingen_coordinates_offset}},
+		noise_generator = noise_generator,
+		static_params = static_params,
+		specials = specials,
+		entities = entities,
+		seed = seed,
+		other_map_generation_data = other_map_generation_data,
+		biter_base_density_scale = Balance.biter_base_density_scale()
+	}
 
 	local tiles_corrected = {}
 	for i = 1, #tiles do
@@ -1810,7 +1849,7 @@ local remove_boost_movement_speed_on_respawn =
 
 		Memory.set_working_id(crew_id)
 		local memory = Memory.get_crew_memory()
-		if not (memory.id and memory.id > 0) then return end --check if crew disbanded
+		if not Common.is_id_valid(memory.id) then return end --check if crew disbanded
 		if memory.game_lost then return end
 		memory.speed_boost_characters[player.index] = nil
 
@@ -1830,7 +1869,7 @@ local boost_movement_speed_on_respawn =
 
 		Memory.set_working_id(crew_id)
 		local memory = Memory.get_crew_memory()
-		if not (memory.id and memory.id > 0) then return end --check if crew disbanded
+		if not Common.is_id_valid(memory.id) then return end --check if crew disbanded
 		if memory.game_lost then return end
 		memory.speed_boost_characters[player.index] = true
 
diff --git a/maps/pirates/api_on_tick.lua b/maps/pirates/api_on_tick.lua
index 580c22f8..afed2e4d 100644
--- a/maps/pirates/api_on_tick.lua
+++ b/maps/pirates/api_on_tick.lua
@@ -1443,7 +1443,7 @@ end
 
 function Public.update_alert_sound_frequency_tracker()
 	local memory = Memory.get_crew_memory()
-	if memory.seconds_until_alert_sound_can_be_played_again > 0 then
+	if memory.seconds_until_alert_sound_can_be_played_again and memory.seconds_until_alert_sound_can_be_played_again > 0 then
 		memory.seconds_until_alert_sound_can_be_played_again = memory.seconds_until_alert_sound_can_be_played_again - 1
 		memory.seconds_until_alert_sound_can_be_played_again = Math.max(0, memory.seconds_until_alert_sound_can_be_played_again)
 	end
diff --git a/maps/pirates/commands.lua b/maps/pirates/commands.lua
index 77b37abd..85710195 100644
--- a/maps/pirates/commands.lua
+++ b/maps/pirates/commands.lua
@@ -156,6 +156,9 @@ commands.add_command(
 function(cmd)
 	cmd_set_memory(cmd)
 
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
+
 	--local param = tostring(cmd.parameter)
 	if check_admin(cmd) then
 		--local player = game.players[cmd.player_index]
@@ -173,6 +176,9 @@ commands.add_command(
 function(cmd)
 	cmd_set_memory(cmd)
 
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
+
 	local param = tostring(cmd.parameter)
 	if check_admin(cmd) then
 		local player = game.players[cmd.player_index]
@@ -190,6 +196,9 @@ commands.add_command(
 function(cmd)
 	cmd_set_memory(cmd)
 
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
+
 	--local param = tostring(cmd.parameter)
 	if check_admin(cmd) then
 		Crew.summon_crew()
@@ -201,6 +210,10 @@ commands.add_command(
 {'pirates.cmd_explain_ok'},
 function(cmd)
 	cmd_set_memory(cmd)
+
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
+
 	local player = game.players[cmd.player_index]
 	if not Common.validate_player(player) then return end
 	
@@ -249,7 +262,7 @@ function(cmd)
 	if not Common.validate_player(player) then return end
 
 	if param and param ~= 'nil' then
-		local string = Roles.get_class_print_string(param, true)
+		local string = Roles.get_class_print_string(param, true, true)
 		if string then
 			Common.notify_player_expected(player, {'', {'pirates.class_definition_for'}, ' ', string})
 		else
@@ -265,6 +278,10 @@ commands.add_command(
 {'pirates.cmd_explain_take'},
 function(cmd)
 	cmd_set_memory(cmd)
+
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
+
 	local param = tostring(cmd.parameter)
 	local player = game.players[cmd.player_index]
 	if not Common.validate_player(player) then return end
@@ -272,7 +289,7 @@ function(cmd)
 	if param and param ~= 'nil' then
 		for _, class in pairs(Classes.enum) do
 			if Classes.eng_form[class]:lower() == param:lower() then
-				Classes.assign_class(player.index, class, true)
+				Classes.assign_class(player.index, class)
 				return true
 			end
 		end
@@ -289,11 +306,15 @@ commands.add_command(
 {'pirates.cmd_explain_giveup'},
 function(cmd)
 	cmd_set_memory(cmd)
+
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
+
 	--local param = tostring(cmd.parameter)
 	local player = game.players[cmd.player_index]
 	if not Common.validate_player(player) then return end
 
-	Classes.try_renounce_class(player, true)
+	Classes.assign_class(player.index, nil)
 end)
 
 commands.add_command(
@@ -371,6 +392,9 @@ commands.add_command(
 function(cmd)
 	cmd_set_memory(cmd)
 
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
+
 	local player = game.players[cmd.player_index]
 	local param = tostring(cmd.parameter)
 	if check_captain_or_admin(cmd) then
@@ -387,6 +411,9 @@ commands.add_command(
 {'pirates.cmd_explain_officer'},
 function(cmd)
 	cmd_set_memory(cmd)
+
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
 	
 	local player = game.players[cmd.player_index]
 	local param = tostring(cmd.parameter)
@@ -409,6 +436,9 @@ commands.add_command(
 {'pirates.cmd_explain_undock'},
 function(cmd)
 	cmd_set_memory(cmd)
+
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
 	
 	--local param = tostring(cmd.parameter)
 	if check_captain_or_admin(cmd) then
@@ -427,6 +457,9 @@ commands.add_command(
 {'pirates.cmd_explain_tax'},
 function(cmd)
 	cmd_set_memory(cmd)
+
+	local memory = Memory.get_crew_memory()
+	if not Common.is_id_valid(memory.id) then return end
 	
 	--local param = tostring(cmd.parameter)
 	if check_captain(cmd) then
diff --git a/maps/pirates/common.lua b/maps/pirates/common.lua
index cfdc6401..c2b6fd14 100644
--- a/maps/pirates/common.lua
+++ b/maps/pirates/common.lua
@@ -112,7 +112,7 @@ end
 function Public.activecrewcount()
 	local global_memory = Memory.get_global_memory()
 	local memory = Memory.get_crew_memory()
-	if memory.id == 0 then return 0 end
+	if not Public.is_id_valid(memory.id) then return 0 end
 
 	local count = 0
 	for _, id in pairs(memory.crewplayerindices) do
@@ -815,7 +815,7 @@ end
 
 function Public.crew_get_crew_members()
 	local memory = Memory.get_crew_memory()
-	if memory.id == 0 then return {} end
+	if not Public.is_id_valid(memory.id) then return {} end
 
 	local playerlist = {}
 	for _, id in pairs(memory.crewplayerindices) do
@@ -828,7 +828,7 @@ end
 
 function Public.crew_get_crew_members_and_spectators()
 	local memory = Memory.get_crew_memory()
-	if memory.id == 0 then return {} end
+	if not Public.is_id_valid(memory.id) then return {} end
 
 	local playerlist = {}
 	for _, id in pairs(memory.crewplayerindices) do
@@ -848,7 +848,7 @@ end
 function Public.crew_get_nonafk_crew_members()
 	local global_memory = Memory.get_global_memory()
 	local memory = Memory.get_crew_memory()
-	if memory.id == 0 then return {} end
+	if not Public.is_id_valid(memory.id) then return {} end
 
 	local playerlist = {}
 	for _, id in pairs(memory.crewplayerindices) do
@@ -1510,4 +1510,12 @@ function Public.get_id_from_force_name(force_name)
 	return tonumber(string.sub(force_name, -3, -1)) or nil
 end
 
+function Public.is_id_valid(id)
+	if id and id ~= 0 then
+		return true
+	else
+		return false
+	end
+end
+
 return Public
\ No newline at end of file
diff --git a/maps/pirates/crew.lua b/maps/pirates/crew.lua
index 3703672f..b1c8b64f 100644
--- a/maps/pirates/crew.lua
+++ b/maps/pirates/crew.lua
@@ -734,6 +734,7 @@ function Public.initialise_crew(accepted_proposal)
 	memory.classes_table = {}
 	memory.officers_table = {}
 	memory.spare_classes = {}
+	memory.unlocked_classes = {}
 
 	memory.healthbars = {}
 	memory.overworld_krakens = {}
@@ -1034,5 +1035,4 @@ function Public.reset_crew_and_enemy_force(id)
 end
 
 
-
 return Public
\ No newline at end of file
diff --git a/maps/pirates/gui/classes.lua b/maps/pirates/gui/classes.lua
new file mode 100644
index 00000000..333c7664
--- /dev/null
+++ b/maps/pirates/gui/classes.lua
@@ -0,0 +1,251 @@
+-- This file is part of thesixthroc's Pirate Ship softmod, licensed under GPLv3 and stored at https://github.com/danielmartin0/ComfyFactorio-Pirates.
+
+
+local Memory = require 'maps.pirates.memory'
+local Common = require 'maps.pirates.common'
+local Classes = require 'maps.pirates.roles.classes'
+local GuiCommon = require 'maps.pirates.gui.common'
+local Public = {}
+
+
+local window_name = 'classes'
+
+local widths = {}
+widths['available_classes'] = 150
+widths['taken_by'] = 150
+widths['action_buttons'] = 100
+
+-- used to track whether new class entries should be added during "full_update"
+local entry_count = 0
+
+local function add_class_entry(player, class, taken_by_player_index, index)
+	if not player.gui.screen[window_name .. '_piratewindow'] then return end
+	local flow
+	flow = player.gui.screen[window_name .. '_piratewindow']
+
+	local class_list_panel_table = flow.scroll_pane.class_list_panel_table
+
+
+	-- Class label
+	local explanation = Classes.explanation_advanced(class, false)
+	local full_explanation
+
+	if Classes.class_purchase_requirement[class] then
+		full_explanation = {'pirates.class_explanation_upgraded_class', Classes.display_form(class), Classes.display_form(Classes.class_purchase_requirement[class]), explanation}
+	else
+		full_explanation = {'pirates.class_explanation', Classes.display_form(class), explanation}
+	end
+
+	local available_class_label = class_list_panel_table.add({
+		type = 'label',
+		caption = Classes.display_form(class),
+		tooltip = full_explanation,
+	})
+	available_class_label.style.minimal_width = widths['available_classes']
+    available_class_label.style.maximal_width = widths['available_classes']
+
+
+	-- Player label
+	local taken_by_player_name = taken_by_player_index and game.players[taken_by_player_index].name or ''
+	local taken_by_label = class_list_panel_table.add({
+		name = 'player_label' .. index,
+		type = 'label',
+		caption = taken_by_player_name,
+	})
+	taken_by_label.style.minimal_width = widths['taken_by']
+    taken_by_label.style.maximal_width = widths['taken_by']
+
+	-- Button
+	local button
+
+	if not taken_by_player_index then
+		button = class_list_panel_table.add({
+			name = 'button' .. index,
+			type = 'button',
+			caption = {'pirates.gui_classes_take'},
+			tooltip = {'pirates.gui_classes_take_enabled_tooltip'},
+		})
+	elseif taken_by_player_index == player.index then
+		button = class_list_panel_table.add({
+			name = 'button' .. index,
+			type = 'button',
+			caption = {'pirates.gui_classes_drop'},
+			tooltip = {'pirates.gui_classes_drop_tooltip'},
+		})
+		button.style.font_color = {r=1, g=0, b=0}
+		button.style.hovered_font_color = {r=1, g=0, b=0}
+		button.style.clicked_font_color = {r=1, g=0, b=0}
+	else
+		button = class_list_panel_table.add({
+			name = 'button' .. index,
+			type = 'button',
+			enabled = false, -- wanted to make "visble = false" instead, but table doesn't like that
+			caption = {'pirates.gui_classes_take'},
+			tooltip = {'pirates.gui_classes_take_disabled_tooltip'},
+		})
+	end
+	button.tags = {type = 'pirates_' .. window_name, index = index}
+
+	button.style.minimal_width = widths['action_buttons']
+	button.style.maximal_width = widths['action_buttons']
+end
+
+function Public.toggle_window(player)
+	local memory = Memory.get_crew_memory()
+	local flow, flow2, flow3, flow4
+
+	--*** OVERALL FLOW ***--
+	if player.gui.screen[window_name .. '_piratewindow'] then player.gui.screen[window_name .. '_piratewindow'].destroy() return end
+
+    if not Common.is_id_valid(memory.id) then return end
+
+	flow = GuiCommon.new_window(player, window_name)
+	flow.caption = {'pirates.gui_classes'}
+	flow.auto_center = true
+	flow.style.maximal_width = 500
+
+	flow2 = flow.add({
+		name = 'headers',
+		type = 'flow',
+		direction = 'horizontal',
+	})
+
+	flow3 = flow2.add({
+		name = 'available_classes',
+		type = 'label',
+		caption = {'pirates.gui_classes_available_classes'},
+	})
+	flow3.style.minimal_width = widths['available_classes']
+    flow3.style.maximal_width = widths['available_classes']
+	flow3.style.font = 'heading-2'
+	flow3.style.font_color = GuiCommon.section_header_font_color
+
+	flow3 = flow2.add({
+		name = 'taken_by',
+		type = 'label',
+		caption = {'pirates.gui_classes_taken_by'},
+	})
+	flow3.style.minimal_width = widths['taken_by']
+    flow3.style.maximal_width = widths['taken_by']
+	flow3.style.font = 'heading-2'
+	flow3.style.font_color = GuiCommon.section_header_font_color
+
+	flow3 = flow2.add({
+		name = 'action_buttons',
+		type = 'label',
+		caption = {'pirates.gui_classes_actions'},
+	})
+	flow3.style.minimal_width = widths['action_buttons']
+    flow3.style.maximal_width = widths['action_buttons']
+	flow3.style.font = 'heading-2'
+	flow3.style.font_color = GuiCommon.section_header_font_color
+
+	-- List management
+    local scroll_pane = flow.add {
+        type = 'scroll-pane',
+        name = 'scroll_pane',
+        direction = 'vertical',
+        horizontal_scroll_policy = 'never',
+        vertical_scroll_policy = 'auto'
+    }
+    scroll_pane.style.maximal_height = 500
+	scroll_pane.style.bottom_padding = 20
+
+	scroll_pane.add{
+		type = 'table',
+		name = 'class_list_panel_table',
+		column_count = 3
+	}
+
+	for i, class_entry in ipairs(memory.unlocked_classes) do
+		add_class_entry(player, class_entry.class, class_entry.taken_by, i)
+	end
+
+	entry_count = #memory.unlocked_classes
+
+	GuiCommon.flow_add_close_button(flow, window_name .. '_piratebutton')
+end
+
+
+
+function Public.full_update(player)
+	if not player.gui.screen[window_name .. '_piratewindow'] then return end
+	local flow = player.gui.screen[window_name .. '_piratewindow']
+
+	local memory = Memory.get_crew_memory()
+
+	--*** Overwrite contents ***--
+
+	local class_list_panel_table = flow.scroll_pane.class_list_panel_table
+
+	-- Currently assuming class list size never decreases
+
+	-- Update current content table
+	for i = 1, entry_count do
+		local label = class_list_panel_table['player_label' .. i]
+		local class_entry = memory.unlocked_classes[i]
+		label.caption = class_entry.taken_by and game.players[class_entry.taken_by].name or ''
+		
+		local black = {r=0, g=0, b=0}
+		local red = {r=1, g=0, b=0}
+
+		local button = class_list_panel_table['button' .. i]
+		if not class_entry.taken_by then
+			button.caption = {'pirates.gui_classes_take'}
+			button.tooltip = {'pirates.gui_classes_take_enabled_tooltip'}
+			button.style.font_color = black
+			button.style.hovered_font_color = black
+			button.style.clicked_font_color = black
+		elseif class_entry.taken_by == player.index then
+			button.caption = {'pirates.gui_classes_drop'}
+			button.tooltip = {'pirates.gui_classes_drop_tooltip'}
+			button.style.font_color = red
+			button.style.hovered_font_color = red
+			button.style.clicked_font_color = red
+		else
+			button.caption = {'pirates.gui_classes_take'}
+			button.tooltip = {'pirates.gui_classes_take_disabled_tooltip'}
+			button.style.font_color = black
+			button.style.hovered_font_color = black
+			button.style.clicked_font_color = black
+		end
+	end
+
+
+	-- If new entries were added since last update, add them to GUI
+	if entry_count ~= #memory.unlocked_classes then
+		for i = entry_count + 1, #memory.unlocked_classes do
+			local class_entry = memory.unlocked_classes[i]
+			add_class_entry(player, class_entry.class, class_entry.taken_by, i)
+		end
+
+		entry_count = #memory.unlocked_classes
+	end
+end
+
+
+function Public.click(event)
+	local player = game.players[event.element.player_index]
+	if not player.gui.screen[window_name .. '_piratewindow'] then return end
+
+	local tags = event.element.tags
+	if not tags then return end
+	if tags.type ~= 'pirates_' .. window_name then return end
+
+	local memory = Memory.get_crew_memory()
+
+	if tags.index then
+		local button_is_take_class = (not memory.unlocked_classes[tags.index].taken_by) and true or false
+
+		if button_is_take_class then
+			local class_to_assign = memory.unlocked_classes[tags.index].class
+			Classes.assign_class(player.index, class_to_assign, tags.index)
+			return
+		else -- button is drop class
+			Classes.assign_class(player.index, nil, tags.index)
+			return
+		end
+	end
+end
+
+return Public
\ No newline at end of file
diff --git a/maps/pirates/gui/common.lua b/maps/pirates/gui/common.lua
index cdbace5d..99f6d35f 100644
--- a/maps/pirates/gui/common.lua
+++ b/maps/pirates/gui/common.lua
@@ -323,7 +323,7 @@ function Public.flow_add_close_button(flow, close_button_name)
 	flow4 = flow3.add({
 		type = 'button',
 		name = close_button_name,
-		caption = 'Close',
+		caption = {'pirates.gui_close_button'},
 	})
 	flow4.style = 'back_button'
 	flow4.style.minimal_width = 90
diff --git a/maps/pirates/gui/crew.lua b/maps/pirates/gui/crew.lua
index c9d30437..aa2fbdd9 100644
--- a/maps/pirates/gui/crew.lua
+++ b/maps/pirates/gui/crew.lua
@@ -4,15 +4,8 @@
 local Memory = require 'maps.pirates.memory'
 local Common = require 'maps.pirates.common'
 local Utils = require 'maps.pirates.utils_local'
--- local Math = require 'maps.pirates.math'
--- local Surfaces = require 'maps.pirates.surfaces.surfaces'
 local Roles = require 'maps.pirates.roles.roles'
-local Classes = require 'maps.pirates.roles.classes'
 local Crew = require 'maps.pirates.crew'
--- local Progression = require 'maps.pirates.progression'
--- local Structures = require 'maps.pirates.structures.structures'
-local _inspect = require 'utils.inspect'.inspect
--- local Boats = require 'maps.pirates.structures.boats.boats'
 local GuiCommon = require 'maps.pirates.gui.common'
 local CoreData = require 'maps.pirates.coredata'
 local Server = require 'utils.server'
@@ -25,13 +18,24 @@ local window_name = 'crew'
 function Public.toggle_window(player)
 	local memory = Memory.get_crew_memory()
 	local flow, flow2, flow3, flow4
+	local window
 
 	--*** OVERALL FLOW ***--
 	if player.gui.screen[window_name .. '_piratewindow'] then player.gui.screen[window_name .. '_piratewindow'].destroy() return end
 
-	if not memory.id then return end
+	if not Common.is_id_valid(memory.id) then return end
 
-	flow = GuiCommon.new_window(player, window_name)
+	window = GuiCommon.new_window(player, window_name)
+
+	flow = window.add {
+        type = 'scroll-pane',
+        name = 'scroll_pane',
+        direction = 'vertical',
+        horizontal_scroll_policy = 'never',
+        vertical_scroll_policy = 'auto'
+    }
+    flow.style.maximal_height = 500
+	flow.style.bottom_padding = 20
 
 	--*** PARAMETERS OF RUN ***--
 
@@ -126,16 +130,6 @@ function Public.toggle_window(player)
 	flow3.style.margin = 2
 	flow3.style.maximal_height = 350
 
-	flow3 = flow2.add({
-		name = 'class_renounce',
-		type = 'button',
-		caption = {'pirates.gui_crew_window_crewmembers_give_up_class'},
-	})
-	flow3.style.minimal_width = 95
-	flow3.style.font = 'default-bold'
-	flow3.style.font_color = {r=0.10, g=0.10, b=0.10}
-	flow3.tooltip = {'pirates.gui_crew_window_crewmembers_give_up_class_tooltip'}
-
 	flow3 = flow2.add({
 		name = 'officer_resign',
 		type = 'button',
@@ -171,53 +165,6 @@ function Public.toggle_window(player)
 		flow3.style.font_color = {r=0.10, g=0.10, b=0.10}
 	end
 
-	--*** SPARE CLASSES ***--
-
-	flow2 = GuiCommon.flow_add_section(flow, 'spare_classes', {'pirates.gui_crew_window_spare_classes'})
-
-	flow3 = flow2.add({
-		name = 'list',
-		type = 'label',
-	})
-	flow3.style.left_margin = 5
-	flow3.style.top_margin = -3
-	flow3.style.bottom_margin = -3
-	flow3.style.single_line = false
-	flow3.style.maximal_width = 160
-	flow3.style.font = 'default-dropdown'
-
-	flow3 = flow2.add({
-		name = 'assign_flow',
-		type = 'flow',
-		direction = 'vertical',
-	})
-	flow3.style.top_margin = 3
-
-	for _, c in pairs(Classes.enum) do
-		flow4 = flow3.add({
-			name = 'assign_class_' .. c,
-			type = 'button',
-			caption = {'pirates.gui_crew_window_assign_class_button', Classes.display_form(c)},
-		})
-		flow4.style.minimal_width = 95
-		flow4.style.font = 'default-bold'
-		flow4.style.font_color = {r=0.10, g=0.10, b=0.10}
-		flow4.tooltip = {'pirates.gui_crew_window_assign_class_button_tooltip', Classes.display_form(c), Classes.explanation(c)}
-		-- flow4.tooltip = 'Give this class to the selected player.'
-	end
-
-	for _, c in pairs(Classes.enum) do
-		flow4 = flow3.add({
-			name = 'selfassign_class_' .. c,
-			type = 'button',
-			caption = {'pirates.gui_crew_window_selfassign_class_button', Classes.display_form(c)},
-		})
-		flow4.style.minimal_width = 95
-		flow4.style.font = 'default-bold'
-		flow4.style.font_color = {r=0.10, g=0.10, b=0.10}
-		flow4.tooltip = {'pirates.gui_crew_window_selfassign_class_button_tooltip', Classes.display_form(c), Classes.explanation(c)}
-	end
-
 	--*** CAPTAIN's ACTIONS ***--
 
 	flow2 = GuiCommon.flow_add_section(flow, 'captain', {'pirates.gui_crew_window_captains_actions'})
@@ -310,16 +257,6 @@ function Public.toggle_window(player)
 	flow3.style.font_color = {r=0.10, g=0.10, b=0.10}
 	flow3.tooltip = {'pirates.gui_crew_window_captains_actions_unmake_officer_tooltip'}
 
-	flow3 = flow2.add({
-		name = 'revoke_class',
-		type = 'button',
-		caption = {'pirates.gui_crew_window_captains_actions_revoke_class'},
-	})
-	flow3.style.minimal_width = 95
-	flow3.style.font = 'default-bold'
-	flow3.style.font_color = {r=0.10, g=0.10, b=0.10}
-	flow3.tooltip = {'pirates.gui_crew_window_captains_actions_revoke_class_tooltip'}
-
 	flow3 = flow2.add({
 		name = 'capn_summon_crew',
 		type = 'button',
@@ -353,9 +290,8 @@ function Public.toggle_window(player)
 	flow2.style.font = 'default'
 	flow2.caption = {'pirates.gui_crew_window_captains_actions_undock_tip'}
 
-	--
 
-	GuiCommon.flow_add_close_button(flow, window_name .. '_piratebutton')
+	GuiCommon.flow_add_close_button(window, window_name .. '_piratebutton')
 end
 
 
@@ -370,58 +306,22 @@ function Public.full_update(player)
 	if Public.regular_update then Public.regular_update(player) end
 
 	if not player.gui.screen[window_name .. '_piratewindow'] then return end
-	local flow = player.gui.screen[window_name .. '_piratewindow']
+	local window = player.gui.screen[window_name .. '_piratewindow']
+	local flow = window.scroll_pane
+
 
 	local memory = Memory.get_crew_memory()
 	local playercrew_status = GuiCommon.crew_overall_state_bools(player.index)
-	-- local destination = Common.current_destination()
 
 
 	--*** WHAT TO SHOW ***--
 
 	flow.difficulty_vote.visible = memory.overworldx and memory.overworldx == 0
 
-	flow.members.body.class_renounce.visible = memory.classes_table and memory.classes_table[player.index]
-
 	flow.members.body.officer_resign.visible = memory.officers_table and memory.officers_table[player.index]
 
-	flow.spare_classes.visible = memory.spare_classes and #memory.spare_classes > 0
-
 	local other_player_selected = flow.members.body.members_listbox.selected_index ~= 0 and tonumber(flow.members.body.members_listbox.get_item(flow.members.body.members_listbox.selected_index)[2]) ~= player.index
 
-	local any_class_button = false
-	for _, c in pairs(Classes.enum) do
-		if memory.spare_classes and Utils.contains(memory.spare_classes, c) and (not (player.controller_type == defines.controllers.spectator)) then
-			if Common.is_captain(player) and memory.crewplayerindices and #memory.crewplayerindices > 1 then
-				if other_player_selected and (not (memory.classes_table[tonumber(flow.members.body.members_listbox.get_item(flow.members.body.members_listbox.selected_index)[2])])) then
-					flow.spare_classes.body.assign_flow['selfassign_class_' .. c].visible = false
-					flow.spare_classes.body.assign_flow['assign_class_' .. c].visible = true
-					any_class_button = true
-				else
-					flow.spare_classes.body.assign_flow['assign_class_' .. c].visible = false
-					if (not memory.classes_table[player.index]) then
-						flow.spare_classes.body.assign_flow['selfassign_class_' .. c].visible = true
-						any_class_button = true
-					else
-						flow.spare_classes.body.assign_flow['selfassign_class_' .. c].visible = false
-					end
-				end
-			else
-				flow.spare_classes.body.assign_flow['assign_class_' .. c].visible = false
-				if (not memory.classes_table[player.index]) then
-					flow.spare_classes.body.assign_flow['selfassign_class_' .. c].visible = true
-					any_class_button = true
-				else
-					flow.spare_classes.body.assign_flow['selfassign_class_' .. c].visible = false
-				end
-			end
-		else
-			flow.spare_classes.body.assign_flow['assign_class_' .. c].visible = false
-			flow.spare_classes.body.assign_flow['selfassign_class_' .. c].visible = false
-		end
-	end
-	flow.spare_classes.body.assign_flow.visible = any_class_button
-
 	flow.captain.visible = Common.is_captain(player)
 	flow.undock_tip.visible = Common.is_captain(player)
 
@@ -431,8 +331,6 @@ function Public.full_update(player)
 	flow.captain.body.make_officer.visible = other_player_selected and (not (memory.officers_table and memory.officers_table[tonumber(flow.members.body.members_listbox.get_item(flow.members.body.members_listbox.selected_index)[2])]))
 	flow.captain.body.unmake_officer.visible = other_player_selected and ((memory.officers_table and memory.officers_table[tonumber(flow.members.body.members_listbox.get_item(flow.members.body.members_listbox.selected_index)[2])]))
 
-	flow.captain.body.revoke_class.visible = other_player_selected and (memory.classes_table[tonumber(flow.members.body.members_listbox.get_item(flow.members.body.members_listbox.selected_index)[2])])
-
 	-- flow.captain.body.capn_undock_normal.visible = memory.boat and memory.boat.state and ((memory.boat.state == Boats.enum_state.LANDED) or (memory.boat.state == Boats.enum_state.APPROACHING) or (memory.boat.state == Boats.enum_state.DOCKED))
 
 	flow.captain.body.capn_summon_crew.visible = false
@@ -467,27 +365,11 @@ function Public.full_update(player)
 
 	--== UPDATE CONTENT ==--
 
-	if memory.id then
-		flow.caption = memory.name
+	if Common.is_id_valid(memory.id) then
+		window.caption = memory.name
 
 		flow.crew_age.caption = {'pirates.gui_crew_window_crew_age', Utils.time_mediumform((memory.age or 0)/60)}
 		flow.crew_capacity_and_difficulty.caption = {'pirates.gui_crew_window_crew_capacity_and_difficulty', CoreData.difficulty_options[memory.difficulty_option].text, CoreData.capacity_options[memory.capacity_option].text3}
-
-		if flow.spare_classes.visible then
-			local str = {''}
-
-			for i, c in ipairs(memory.spare_classes) do
-				if i>1 then
-					str[#str+1] = {'', {'pirates.separator_1'}, Classes.display_form(c)} -- we need to do nesting here, because you can't contanenate more than 20 localised strings. Watch out!
-					--@TODO: In fact we should nest iteratively, as this still caps out around 19 classes.
-				else
-					str[#str+1] = {'', Classes.display_form(c)}
-				end
-			end
-			str[#str+1] = '.'
-
-			flow.spare_classes.body.list.caption = str
-		end
 	end
 
 
@@ -563,18 +445,6 @@ function Public.click(event)
 	-- 	return
 	-- end
 
-
-	if string.sub(eventname, 1, 13) and string.sub(eventname, 1, 13) == 'assign_class_' then
-		local other_id = tonumber(flow.members.body.members_listbox.get_item(flow.members.body.members_listbox.selected_index)[2])
-		Classes.assign_class(other_id, string.sub(eventname, 14, -1))
-		return
-	end
-
-	if string.sub(eventname, 1, 17) and string.sub(eventname, 1, 17) == 'selfassign_class_' then
-		Classes.assign_class(player.index, string.sub(eventname, 18, -1), true)
-		return
-	end
-
 	if string.sub(eventname, 1, 18) and string.sub(eventname, 1, 18) == 'difficulty_option_' then
 		Crew.difficulty_vote(player.index, tonumber(string.sub(eventname, 19, -1)))
 		return
@@ -597,11 +467,6 @@ function Public.click(event)
 		return
 	end
 
-	if eventname == 'class_renounce' then
-		Classes.try_renounce_class(player, true)
-		return
-	end
-
 	if eventname == 'capn_renounce' then
 		Roles.renounce_captainhood(player)
 		return
@@ -653,12 +518,6 @@ function Public.click(event)
 		return
 	end
 
-	if eventname == 'revoke_class' then
-		local other_id = tonumber(flow.members.body.members_listbox.get_item(flow.members.body.members_listbox.selected_index)[2])
-		Roles.revoke_class(player, game.players[other_id])
-		return
-	end
-
 	if eventname == 'capn_plank' then
 		local other_id = tonumber(flow.members.body.members_listbox.get_item(flow.members.body.members_listbox.selected_index)[2])
 
diff --git a/maps/pirates/gui/gui.lua b/maps/pirates/gui/gui.lua
index 89225f3d..12ea8ffa 100644
--- a/maps/pirates/gui/gui.lua
+++ b/maps/pirates/gui/gui.lua
@@ -9,6 +9,7 @@ local GuiEvo = require 'maps.pirates.gui.evo'
 local GuiProgress = require 'maps.pirates.gui.progress'
 local GuiRuns = require 'maps.pirates.gui.runs'
 local GuiCrew = require 'maps.pirates.gui.crew'
+local GuiClasses = require 'maps.pirates.gui.classes'
 local GuiFuel = require 'maps.pirates.gui.fuel'
 local GuiMinimap = require 'maps.pirates.gui.minimap'
 local GuiInfo = require 'maps.pirates.gui.info'
@@ -45,6 +46,7 @@ Public.enum = enum
 Public.progress = require 'maps.pirates.gui.progress'
 Public.runs = require 'maps.pirates.gui.runs'
 Public.crew = require 'maps.pirates.gui.crew'
+Public.classes = require 'maps.pirates.gui.classes'
 Public.fuel = require 'maps.pirates.gui.fuel'
 Public.minimap = require 'maps.pirates.gui.minimap'
 Public.info = require 'maps.pirates.gui.info'
@@ -101,6 +103,9 @@ local function create_gui(player)
 	flow2 = GuiCommon.flow_add_floating_sprite_button(flow1, 'crew_piratebutton')
 	flow2.sprite = 'utility/spawn_flag'
 
+	flow2 = GuiCommon.flow_add_floating_sprite_button(flow1, 'classes_piratebutton')
+	flow2.sprite = 'item/light-armor'
+
 	-- flow2 = GuiCommon.flow_add_floating_sprite_button(flow1, 'lives_piratebutton')
 	-- flow2.tooltip = 'Lives\n\nWhen a silo is destroyed before its rocket is launched, you lose a life.\n\nLosing all your lives is one way to lose the game.'
 	-- flow2.mouse_button_filter = {'middle'}
@@ -902,7 +907,7 @@ function Public.update_gui(player)
 
 	flow1 = pirates_flow.crew_piratebutton_frame.crew_piratebutton
 
-	if memory.id and memory.id ~= 0 then
+	if Common.is_id_valid(memory.id) then
 		flow1.tooltip = {'pirates.gui_crew_tooltip_1'}
 		flow1.mouse_button_filter = {'left','right'}
 	else
@@ -913,10 +918,24 @@ function Public.update_gui(player)
 		end
 	end
 
+	flow1 = pirates_flow.classes_piratebutton_frame.classes_piratebutton
+
+	if Common.is_id_valid(memory.id) then
+		flow1.tooltip = {'pirates.gui_classes_tooltip_1'}
+		flow1.mouse_button_filter = {'left','right'}
+	else
+		flow1.tooltip = {'pirates.gui_classes_tooltip_2'}
+		flow1.mouse_button_filter = {'middle'} --hack to avoid press visual
+		if player.gui.screen['classes_piratewindow'] then
+			player.gui.screen['classes_piratewindow'].destroy()
+		end
+	end
+
 	if GuiEvo.full_update then GuiEvo.full_update(player) end
 	if GuiProgress.regular_update then GuiProgress.regular_update(player) end --moved to event
 	if GuiRuns.full_update then GuiRuns.full_update(player) end
 	if GuiCrew.full_update then GuiCrew.full_update(player) end
+	if GuiClasses.full_update then GuiClasses.full_update(player) end
 	if GuiFuel.regular_update then GuiFuel.regular_update(player) end --moved to event
 	if GuiMinimap.full_update then GuiMinimap.full_update(player) end
 	if GuiInfo.full_update then GuiInfo.full_update(player) end
@@ -961,7 +980,7 @@ function Public.update_gui(player)
 	flow1 = pirates_flow.progress_piratebutton_frame.progress_piratebutton
 
 	flow1.number = (memory.overworldx or 0)
-	flow1.caption = {'pirates.gui_progress_tooltip', memory.overworldx or 0, CoreData.victory_x}
+	flow1.tooltip = {'pirates.gui_progress_tooltip', memory.overworldx or 0, CoreData.victory_x}
 	-- pirates_flow.destination_piratebutton_frame.destination_piratebutton.number = memory.destinationsvisited_indices and #memory.destinationsvisited_indices or 0
 
 
@@ -1201,6 +1220,7 @@ local function on_gui_click(event)
 	else
 		if GuiRuns.click then GuiRuns.click(event) end
 		if GuiCrew.click then GuiCrew.click(event) end
+		if GuiClasses.click then GuiClasses.click(event) end
 		if GuiFuel.click then GuiFuel.click(event) end
 		if GuiMinimap.click then GuiMinimap.click(event) end
 		if GuiInfo.click then GuiInfo.click(event) end
diff --git a/maps/pirates/memory.lua b/maps/pirates/memory.lua
index aedb8302..e76d7694 100644
--- a/maps/pirates/memory.lua
+++ b/maps/pirates/memory.lua
@@ -78,6 +78,8 @@ function Public.initialise_crew_memory(id) --mostly serves as a dev reference of
 	memory.boat = nil
 
 	memory.available_classes_pool = nil
+	-- Duplicating unlocked classes data for consistency reasons (this way, entries will remain in the same order when unlocked class data changes)
+	memory.unlocked_classes = nil
 
 	memory.seconds_until_alert_sound_can_be_played_again = 0
 	memory.crewplayerindices = nil
diff --git a/maps/pirates/progression.lua b/maps/pirates/progression.lua
index fc01c447..acf0ca9c 100644
--- a/maps/pirates/progression.lua
+++ b/maps/pirates/progression.lua
@@ -546,7 +546,7 @@ local parrot_set_sail_advice =
 		Memory.set_working_id(crew_id)
 
 		local memory = Memory.get_crew_memory()
-		if not (memory.id and memory.id > 0) then return end --check if crew disbanded
+		if not Common.is_id_valid(memory.id) then return end --check if crew disbanded
 		if memory.game_lost then return end
 
 		if memory.boat and memory.boat.state and memory.boat.state == Boats.enum_state.ATSEA_WAITING_TO_SAIL then
diff --git a/maps/pirates/roles/classes.lua b/maps/pirates/roles/classes.lua
index 157f62c2..7b47eb02 100644
--- a/maps/pirates/roles/classes.lua
+++ b/maps/pirates/roles/classes.lua
@@ -70,7 +70,7 @@ function Public.explanation(class)
 	return {'pirates.class_' .. class .. '_explanation'}
 end
 
-function Public.explanation_advanced(class)
+function Public.explanation_advanced(class, add_is_class_obstainable)
 	local explanation = 'pirates.class_' .. class .. '_explanation_advanced'
 	local full_explanation
 
@@ -124,7 +124,9 @@ function Public.explanation_advanced(class)
 		full_explanation = {'', {explanation}}
 	end
 
-	full_explanation[#full_explanation + 1] = Public.class_is_obtainable(class) and {'', ' ', {'pirates.class_obtainable'}} or {'', ' ', {'pirates.class_unobtainable'}}
+	if add_is_class_obstainable then
+		full_explanation[#full_explanation + 1] = Public.class_is_obtainable(class) and {'', ' ', {'pirates.class_obtainable'}} or {'', ' ', {'pirates.class_unobtainable'}}
+	end
 
 	return full_explanation
 end
@@ -204,59 +206,61 @@ function Public.class_is_obtainable(class)
 	return false
 end
 
-
-function Public.assign_class(player_index, class, self_assigned)
+-- When "class" is nil, player drops equipped class
+-- "class_entry_index" only relevant for GUI order consistency
+function Public.assign_class(player_index, class, class_entry_index)
 	local memory = Memory.get_crew_memory()
 	local player = game.players[player_index]
 
 	if not memory.classes_table then memory.classes_table = {} end
 
-	if memory.classes_table[player_index] == class then
-		Common.notify_player_error(player, {'pirates.error_class_assign_redundant', Public.display_form(class)})
-		return false
-	end
 
-	if Utils.contains(memory.spare_classes, class) then -- verify that one is spare
+	if class then
+		if Utils.contains(memory.spare_classes, class) then
+			-- drop class
+			if memory.classes_table[player_index] then
+				memory.spare_classes[#memory.spare_classes + 1] = memory.classes_table[player_index]
+				memory.classes_table[player_index] = nil
 
-		Public.try_renounce_class(player, false)
-
-		memory.classes_table[player_index] = class
-
-		local force = memory.force
-		if force and force.valid then
-			if self_assigned then
-				Common.notify_force_light(force,{'pirates.class_take_spare', player.name, Public.display_form(memory.classes_table[player_index]), Public.explanation(memory.classes_table[player_index])})
-			else
-				Common.notify_force_light(force,{'pirates.class_give_spare', Public.display_form(memory.classes_table[player_index]), player.name, Public.explanation(memory.classes_table[player_index])})
-			end
-		end
-
-		memory.spare_classes = Utils.ordered_table_with_single_value_removed(memory.spare_classes, class)
-		return true
-	else
-		Common.notify_player_error(player, {'pirates.error_class_assign_unavailable_class'})
-		return false
-	end
-end
-
-function Public.try_renounce_class(player, whisper_failure_message, impersonal_bool)
-	local memory = Memory.get_crew_memory()
-
-	local force = memory.force
-	if force and force.valid and player and player.index then
-		if memory.classes_table and memory.classes_table[player.index] then
-			if force and force.valid then
-				if impersonal_bool then
-					Common.notify_force_light(force,{'pirates.class_becomes_spare', Public.display_form(memory.classes_table[player.index])})
-				else
-					Common.notify_force_light(force,{'pirates.class_give_up', player.name, Public.display_form(memory.classes_table[player.index])})
+				for _, class_entry in ipairs(memory.unlocked_classes) do
+					if class_entry.taken_by == player.index then
+						class_entry.taken_by = nil
+						break
+					end
 				end
 			end
 
-			memory.spare_classes[#memory.spare_classes + 1] = memory.classes_table[player.index]
-			memory.classes_table[player.index] = nil
-		elseif whisper_failure_message then
-			Common.notify_player_error(player, {'pirates.class_give_up_error_no_class'})
+			-- assign class
+			memory.classes_table[player_index] = class
+			memory.spare_classes = Utils.ordered_table_with_single_value_removed(memory.spare_classes, class)
+
+			if class_entry_index then
+				memory.unlocked_classes[class_entry_index].taken_by = player.index
+			else
+				for _, class_entry in ipairs(memory.unlocked_classes) do
+					if class_entry.class == class and (not class_entry.taken_by) then
+						class_entry.taken_by = player.index
+						break
+					end
+				end
+			end
+		end
+	else
+		-- drop class
+		if memory.classes_table[player_index] then
+			memory.spare_classes[#memory.spare_classes + 1] = memory.classes_table[player_index]
+			memory.classes_table[player_index] = nil
+
+			if class_entry_index then
+				memory.unlocked_classes[class_entry_index].taken_by = nil
+			else
+				for _, class_entry in ipairs(memory.unlocked_classes) do
+					if class_entry.taken_by == player.index then
+						class_entry.taken_by = nil
+						break
+					end
+				end
+			end
 		end
 	end
 end
@@ -380,6 +384,78 @@ function Public.lumberjack_bonus_items(give_table)
 	end
 end
 
+function Public.try_unlock_class(class_for_sale, player, force_unlock)
+	local memory = Memory.get_crew_memory()
+
+	local required_class = Public.class_purchase_requirement[class_for_sale]
+
+	if not (memory.classes_table and memory.spare_classes) then
+		return false
+	end
+
+	if required_class then
+		local chosen_class_assigned = false
+
+		for p_index, chosen_class in pairs(memory.classes_table) do
+			if chosen_class == required_class then
+				memory.classes_table[p_index] = class_for_sale
+				chosen_class_assigned = true
+
+				-- update GUI data
+				for _, class_entry in ipairs(memory.unlocked_classes) do
+					if class_entry.taken_by == player.index then
+						class_entry.class = class_for_sale
+						break
+					end
+				end
+				return true
+			end
+		end
+
+		if not chosen_class_assigned then
+			for i, spare_class in pairs(memory.spare_classes) do
+				if spare_class == required_class then
+					memory.spare_classes[i] = class_for_sale
+
+					-- update GUI data
+					for _, class_entry in ipairs(memory.unlocked_classes) do
+						if required_class == class_entry.class and (not class_entry.taken_by) then
+							class_entry.class = class_for_sale
+							break
+						end
+					end
+					return true
+				end
+			end
+		end
+
+		-- allows to unlock class even if pre-requisite is missing
+		if force_unlock then
+			memory.spare_classes[#memory.spare_classes + 1] = class_for_sale
+
+			-- update GUI data
+			memory.unlocked_classes[#memory.unlocked_classes + 1] = {class = class_for_sale}
+		end
+	else -- there is no required class
+		-- if player who unlocked class doesn't have one equipped, equip it for him
+		if not memory.classes_table[player.index] then
+			memory.classes_table[player.index] = class_for_sale
+
+			-- update GUI data
+			memory.unlocked_classes[#memory.unlocked_classes + 1] = {class = class_for_sale, taken_by = player.index}
+		else
+			memory.spare_classes[#memory.spare_classes + 1] = class_for_sale
+
+			-- update GUI data
+			memory.unlocked_classes[#memory.unlocked_classes + 1] = {class = class_for_sale}
+		end
+		return true
+	end
+
+	return false
+end
+
+
 
 local event = require 'utils.event'
 event.add(defines.events.on_player_used_capsule, class_on_player_used_capsule)
diff --git a/maps/pirates/roles/roles.lua b/maps/pirates/roles/roles.lua
index adb98b1a..8c7e6b67 100644
--- a/maps/pirates/roles/roles.lua
+++ b/maps/pirates/roles/roles.lua
@@ -74,17 +74,17 @@ function Public.unmake_officer(captain, player)
 	end
 end
 
-function Public.revoke_class(captain, player)
-	local memory = Memory.get_crew_memory()
-	local force = memory.force
+-- function Public.revoke_class(captain, player)
+-- 	local memory = Memory.get_crew_memory()
+-- 	local force = memory.force
 
-	if force and force.valid and player.index and memory.classes_table[player.index] then
-		memory.spare_classes[#memory.spare_classes + 1] = memory.classes_table[player.index]
-		memory.classes_table[player.index] = nil
+-- 	if force and force.valid and player.index and memory.classes_table[player.index] then
+-- 		memory.spare_classes[#memory.spare_classes + 1] = memory.classes_table[player.index]
+-- 		memory.classes_table[player.index] = nil
 
-		Common.notify_force_light(captain,{'pirates.class_revoke', captain.name, Classes.display_form(memory.classes_table[player.index]), player.name})
-	end
-end
+-- 		Common.notify_force_light(captain,{'pirates.class_revoke', captain.name, Classes.display_form(memory.classes_table[player.index]), player.name})
+-- 	end
+-- end
 
 function Public.tag_text(player)
 	local memory = Memory.get_crew_memory()
@@ -92,7 +92,7 @@ function Public.tag_text(player)
 	local str = ''
 	local tags = {}
 
-	if memory.id ~= 0 and Common.is_captain(player) then
+	if Common.is_id_valid(memory.id) and Common.is_captain(player) then
 		tags[#tags + 1] = 'Cap\'n'
 	elseif player.controller_type == defines.controllers.spectator then
 		tags[#tags + 1] = 'Spectating'
@@ -131,13 +131,13 @@ end
 -- 	return str
 -- end
 
-function Public.get_class_print_string(class, full)
+function Public.get_class_print_string(class, full, add_is_class_obstainable)
 
 	for _, class2 in pairs(Classes.enum) do
 		if Classes.eng_form[class2]:lower() == class:lower() or class2 == class:lower() then
 			local explanation
 			if full then
-				explanation = Classes.explanation_advanced(class2)
+				explanation = Classes.explanation_advanced(class2, add_is_class_obstainable)
 			else
 				explanation = Classes.explanation(class2)
 			end
@@ -164,7 +164,7 @@ end
 function Public.player_privilege_level(player)
 	local memory = Memory.get_crew_memory()
 
-	if memory.id ~= 0 and Common.is_captain(player) then
+	if Common.is_id_valid(memory.id) and Common.is_captain(player) then
 		return Public.privilege_levels.CAPTAIN
 	elseif memory.officers_table and memory.officers_table[player.index] then
 		return Public.privilege_levels.OFFICER
@@ -215,18 +215,31 @@ end
 function Public.player_left_so_redestribute_roles(player)
 	-- local memory = Memory.get_crew_memory()
 
-	if player and player.index then
-		if Common.is_captain(player) then
-			Public.assign_captain_based_on_priorities()
-		end
+	if not (player and player.index) then return end
 
-		-- no need to do this, as long as officers get reset when the captainhood changes hands
-		-- if memory.officers_table and memory.officers_table[player.index] then
-		-- 	memory.officers_table[player.index] = nil
-		-- end
+	if Common.is_captain(player) then
+		Public.assign_captain_based_on_priorities()
 	end
 
-	Classes.try_renounce_class(player, false, true)
+	-- no need to do this, as long as officers get reset when the captainhood changes hands
+	-- if memory.officers_table and memory.officers_table[player.index] then
+	-- 	memory.officers_table[player.index] = nil
+	-- end
+
+	local memory = Memory.get_crew_memory()
+
+	-- free up the class
+	if memory.classes_table and memory.classes_table[player.index] then
+		memory.spare_classes[#memory.spare_classes + 1] = memory.classes_table[player.index]
+		memory.classes_table[player.index] = nil
+
+		for _, class_entry in ipairs(memory.unlocked_classes) do
+			if class_entry.taken_by == player.index then
+				class_entry.taken_by = nil
+				break
+			end
+		end
+	end
 end
 
 
@@ -274,7 +287,7 @@ function Public.confirm_captain_exists(player_to_make_captain_otherwise)
 	local memory = Memory.get_crew_memory()
 	-- Currently this catches an issue where a crew drops to zero players, and then someone else joins.
 
-	if (memory.id and memory.id > 0 and memory.crewstatus and memory.crewstatus == 'adventuring') and (not (memory.playerindex_captain and game.players[memory.playerindex_captain] and Common.validate_player(game.players[memory.playerindex_captain]))) then --fixme: enum hacked
+	if (Common.is_id_valid(memory.id) and memory.crewstatus and memory.crewstatus == 'adventuring') and (not (memory.playerindex_captain and game.players[memory.playerindex_captain] and Common.validate_player(game.players[memory.playerindex_captain]))) then --fixme: enum hacked
 		if player_to_make_captain_otherwise then
 			Public.make_captain(player_to_make_captain_otherwise)
 			-- game.print('Auto-reassigning captain.')
diff --git a/maps/pirates/shop/shop.lua b/maps/pirates/shop/shop.lua
index 39477e1c..1b011818 100644
--- a/maps/pirates/shop/shop.lua
+++ b/maps/pirates/shop/shop.lua
@@ -211,41 +211,7 @@ function Public.event_on_market_item_purchased(event)
 				-- if not class_for_sale then return end
 				local required_class = Classes.class_purchase_requirement[class_for_sale]
 
-				local ok = false
-
-				if memory.classes_table and memory.spare_classes then
-					if required_class then
-						local chosen_class_assigned = false
-
-						if required_class then
-							for p_index, chosen_class in pairs(memory.classes_table) do
-								if chosen_class == required_class then
-									memory.classes_table[p_index] = class_for_sale
-									chosen_class_assigned = true
-									ok = true
-									break
-								end
-							end
-						end
-
-						if not chosen_class_assigned then
-							for i, spare_class in pairs(memory.spare_classes) do
-								if spare_class == required_class then
-									memory.spare_classes[i] = class_for_sale
-									ok = true
-									break
-								end
-							end
-						end
-					else -- there is no required class
-						if not memory.classes_table[player.index] then
-							memory.classes_table[player.index] = class_for_sale
-						else
-							memory.spare_classes[#memory.spare_classes + 1] = class_for_sale
-						end
-						ok = true
-					end
-				end
+				local ok = Classes.try_unlock_class(class_for_sale, player)
 
 				if ok then
 					if force and force.valid then
@@ -266,7 +232,7 @@ function Public.event_on_market_item_purchased(event)
 							memory.available_classes_pool[#memory.available_classes_pool + 1] = upgrade
 						end
 					end
-				else
+				else -- if this happens, I believe there is something wrong with code
 					if force and force.valid then
 						Common.notify_force_error(force, {'pirates.class_purchase_error_prerequisite_class', Classes.display_form(required_class)})
 					end
@@ -278,6 +244,8 @@ function Public.event_on_market_item_purchased(event)
 						inv.insert{name = p.name, count = p.amount}
 					end
 					refunds = refunds + 1
+
+					log('Error purchasing class: ' .. class_for_sale)
 				end
 			else
 				Common.notify_force_light(player.force, {'pirates.market_event_buy', player.name, thisPurchaseData.offer_giveitem_count .. ' ' .. thisPurchaseData.offer_giveitem_name, thisPurchaseData.price[1].amount .. ' ' .. thisPurchaseData.price[1].name})
diff --git a/maps/pirates/surfaces/sea/kraken.lua b/maps/pirates/surfaces/sea/kraken.lua
index 24623c1a..697d2a46 100644
--- a/maps/pirates/surfaces/sea/kraken.lua
+++ b/maps/pirates/surfaces/sea/kraken.lua
@@ -54,7 +54,7 @@ local swimming_biters_tick_token =
 function Public.swimming_biters_tick(crew_id, kraken_id)
 	Memory.set_working_id(crew_id)
 	local memory = Memory.get_crew_memory()
-	if not (memory.id and memory.id > 0) then return end --check if crew disbanded
+	if not Common.is_id_valid(memory.id) then return end --check if crew disbanded
 	if memory.game_lost then return end
 	local kraken_data = memory.active_sea_enemies.krakens[kraken_id]
 	if not kraken_data then return end --check if kraken died
@@ -87,7 +87,7 @@ end
 function Public.kraken_tick(crew_id, kraken_id, step, substep)
 	Memory.set_working_id(crew_id)
 	local memory = Memory.get_crew_memory()
-	if not (memory.id and memory.id > 0) then return end --check if crew disbanded
+	if not Common.is_id_valid(memory.id) then return end --check if crew disbanded
 	if memory.game_lost then return end
 	local kraken_data = memory.active_sea_enemies.krakens[kraken_id]
 	if not kraken_data then return end --check if kraken died
diff --git a/maps/pirates/surfaces/surfaces.lua b/maps/pirates/surfaces/surfaces.lua
index 4f2bc799..525d5df0 100644
--- a/maps/pirates/surfaces/surfaces.lua
+++ b/maps/pirates/surfaces/surfaces.lua
@@ -338,16 +338,17 @@ function Public.destination_on_arrival(destination)
 		-- add special chunk structures(small mining base, etc.) to avoid list
 		local structures = destination.dynamic_data.structures_waiting_to_be_placed
 
-		for i = #structures, 1, -1 do
-			local structure = structures[i]
-			local special = structure.data
-			local position = special.position
-			local avoid_radius = math.sqrt(special.width * special.width + special.height * special.height) / 2 + 4
+		if structures then
+			for i = #structures, 1, -1 do
+				local structure = structures[i]
+				local special = structure.data
+				local position = special.position
+				local avoid_radius = math.sqrt(special.width * special.width + special.height * special.height) / 2 + 5
 
-			points_to_avoid[#points_to_avoid + 1] = {x = position.x, y = position.y, r = avoid_radius}
+				points_to_avoid[#points_to_avoid + 1] = {x = position.x, y = position.y, r = avoid_radius}
+			end
 		end
 
-
 		-- game.print('spawning silo')
 		if destination.subtype ~= Islands.enum.RADIOACTIVE then
 			local silo_position = Islands.spawn_silo_setup(points_to_avoid)