diff --git a/config.lua b/config.lua
index 1972031e..d1c15732 100644
--- a/config.lua
+++ b/config.lua
@@ -68,7 +68,26 @@ global.config = {
     -- adds a market
     market = {
         enabled = true,
-        currency = currency
+        currency = currency,
+
+        -- defines the chance that killing an entity will drop coins and the min and max it can drop upon death
+        entity_drop_amount = {
+            ['biter-spawner'] = {low = 5, high = 15, chance = 1},
+            ['spitter-spawner'] = {low = 5, high = 15, chance = 1},
+            ['small-worm-turret'] = {low = 2, high = 8, chance = 1},
+            ['medium-worm-turret'] = {low = 5, high = 15, chance = 1},
+            ['big-worm-turret'] = {low = 10, high = 20, chance = 1},
+
+            -- default is 0, no chance of coins dropping from biters/spitters
+            ['small-biter'] = {low = 1, high = 5, chance = 0},
+            ['small-spitter'] = {low = 1, high = 2, chance = 0},
+            ['medium-spitter'] = {low = 1, high = 3, chance = 0},
+            ['big-spitter'] = {low = 1, high = 3, chance = 0},
+            ['behemoth-spitter'] = {low = 1, high = 10, chance = 0},
+            ['medium-biter']  = {low = 1, high = 3, chance = 0},
+            ['big-biter']  = {low = 1, high = 5, chance = 0},
+            ['behemoth-biter']  = {low = 1, high = 10, chance = 0}
+        }
     },
     -- adds anti-nuke griefing
     nuke_control = {
diff --git a/features/market.lua b/features/market.lua
index 9dd35238..5510398c 100644
--- a/features/market.lua
+++ b/features/market.lua
@@ -17,6 +17,7 @@ local random = math.random
 local format = string.format
 local get_random = table.get_random
 local currency = global.config.market.currency
+local entity_drop_amount = global.config.market.entity_drop_amount
 
 -- local vars
 
@@ -87,18 +88,11 @@ local function pre_player_mined_item(event)
     end
 end
 
-local entity_drop_amount = {
-    ['biter-spawner'] = {low = 5, high = 15},
-    ['spitter-spawner'] = {low = 5, high = 15},
-    ['small-worm-turret'] = {low = 2, high = 8},
-    ['medium-worm-turret'] = {low = 5, high = 15},
-    ['big-worm-turret'] = {low = 10, high = 20}
-}
-
 local spill_items = Token.register(function(data)
     data.surface.spill_item_stack(data.position, {name = currency, count = data.count}, true)
 end)
 
+-- Determines how many coins to drop when enemy entity dies based upon the entity_drop_amount table in config.lua
 local function fish_drop_entity_died(event)
     local entity = event.entity
     if not entity or not entity.valid then
@@ -110,10 +104,14 @@ local function fish_drop_entity_died(event)
         return
     end
 
-    local count = random(bounds.low, bounds.high)
 
-    if count > 0 then
-        Task.set_timeout_in_ticks(1, spill_items, {count = count, surface = entity.surface, position = entity.position})
+    local chance = bounds.chance
+    if chance == 1 or random() <= chance then
+        local count = random(bounds.low, bounds.high)
+        if count > 0 then
+            Task.set_timeout_in_ticks(1, spill_items, {count = count, surface = entity.surface, position = entity.position}
+        )
+        end
     end
 end
 
diff --git a/map_gen/presets/grid_bot_islands.lua b/map_gen/presets/grid_bot_islands.lua
new file mode 100644
index 00000000..d4e08560
--- /dev/null
+++ b/map_gen/presets/grid_bot_islands.lua
@@ -0,0 +1,390 @@
+--[[
+This map uses custom ore gen. When generating the map, under the resource settings tab use Size = 'None' for all resources.
+]]
+local b = require 'map_gen.shared.builders'
+local Random = require 'map_gen.shared.random'
+local degrees = require "utils.math".degrees
+local math = require "utils.math"
+local table = require "utils.table"
+local Perlin = require 'map_gen.shared.perlin_noise'
+local ore_seed1 = 1000
+local ore_seed2 = ore_seed1 * 2
+local enemy_seed = 420420
+
+local Event = require 'utils.event'
+local Retailer = require 'features.retailer'
+
+local RS = require 'map_gen.shared.redmew_surface'
+local MGSP = require 'resources.map_gen_settings'
+RS.set_map_gen_settings(
+    {
+        MGSP.ore_oil_none,
+        MGSP.cliff_none,
+        MGSP.grass_only,
+        MGSP.enemy_none
+    }
+)
+
+-- Overwrite default config for biter coin drop chances to give the players some extra coins to spend on logi bots
+local market = global.config.market
+market.entity_drop_amount = {
+    ['biter-spawner'] = {low = 5, high = 15, chance = 1},
+    ['spitter-spawner'] = {low = 5, high = 15, chance = 1},
+    ['small-worm-turret'] = {low = 2, high = 8, chance = 1},
+    ['medium-worm-turret'] = {low = 5, high = 15, chance = 1},
+    ['big-worm-turret'] = {low = 10, high = 20, chance = 1},
+
+    -- default is 0
+    ['small-biter'] = {low = 1, high = 2, chance = 0.1},
+    ['small-spitter'] = {low = 1, high = 2, chance = 0.05},
+    ['medium-spitter'] = {low = 1, high = 3, chance = 0.05},
+    ['big-spitter'] = {low = 1, high = 3, chance = 0.05},
+    ['behemoth-spitter'] = {low = 1, high = 10, chance = 0.05},
+    ['medium-biter']  = {low = 1, high = 3, chance = 0.05},
+    ['big-biter']  = {low = 1, high = 5, chance = 0.05},
+    ['behemoth-biter']  = {low = 1, high = 10, chance = 0.05}
+}
+
+-- Setup the scenario map information because everyone gets upset if you don't
+local ScenarioInfo = require 'features.gui.info'
+ScenarioInfo.set_map_name('Grid Bot Islands')
+ScenarioInfo.set_map_description('Grid islands with island-based ore mining and deathworld biter settings')
+ScenarioInfo.set_map_extra_info('- Mine the islands with your bots\n- Buy more bots and chests from the market\n- Defend from the hordes of biters!!\n- Earn gold from killing worms and nests and mining trees and rocks')
+
+-- Modify the player starting items to kickstart island mining
+local player_create = global.config.player_create
+player_create.starting_items = {
+    {name = 'modular-armor', count = 1},
+    {name = 'solar-panel-equipment', count = 7},
+    {name = 'battery-equipment', count = 2},
+    {name = 'personal-roboport-equipment', count = 2},
+    {name = 'construction-robot', count = 25},
+    {name = 'iron-gear-wheel', count = 8},
+    {name = 'iron-plate', count = 16}
+}
+
+-- Begin map layout stuff
+local h_track = {
+    b.line_x(2),
+    b.translate(b.line_x(2), 0, -3),
+    b.translate(b.line_x(2), 0, 3),
+    b.rectangle(2, 10)
+}
+
+h_track = b.any(h_track)
+h_track = b.single_x_pattern(h_track, 15)
+
+local v_track = {
+    b.line_y(2),
+    b.translate(b.line_y(2), -3, 0),
+    b.translate(b.line_y(2), 3, 0),
+    b.rectangle(10, 2)
+}
+
+v_track = b.any(v_track)
+v_track = b.single_y_pattern(v_track, 15)
+
+local square = b.rectangle(130, 130)
+
+local ore_square = b.rectangle(20,20)
+local small_ore_square = b.rectangle(18,18)
+
+local leg = b.rectangle(32, 480)
+local head = b.translate(b.oval(32, 64), 0, -64)
+local body = b.translate(b.circle(64), 0, 64)
+
+local count = 10
+local angle = 360 / count
+local list = {head, body}
+for i = 1, (count / 2) - 1 do
+    local shape = b.rotate(leg, degrees(i * angle))
+    table.insert(list, shape)
+end
+
+local spider = b.any(list)
+
+-- Change ore values based upon distance from 0,0
+local function value(base, mult, pow)
+    return function(x, y)
+        local d_sq = x * x + y * y
+        return base + mult * d_sq ^ ( pow / 2 ) -- d ^ pow
+    end
+end
+
+local function non_transform(shape)
+    return shape
+end
+
+local function uranium_transform(shape)
+    return b.scale(shape, 0.5)
+end
+
+local function oil_transform(shape)
+    shape = b.scale(shape, 0.5)
+    return shape
+end
+
+local ores = {
+    {transform = non_transform, resource = 'iron-ore', value = value(500, 0.75, 1.1), weight = 16},
+    {transform = non_transform, resource = 'copper-ore', value = value(400, 0.75, 1.1), weight = 10},
+    {transform = non_transform, resource = 'stone', value = value(250, 0.3, 1.05), weight = 3},
+    {transform = non_transform, resource = 'coal', value = value(400, 0.8, 1.075), weight = 5},
+    {transform = uranium_transform, resource = 'uranium-ore', value = value(200, 0.3, 1.025), weight = 3},
+    {transform = oil_transform, resource = 'crude-oil', value = value(60000, 50, 1.025), weight = 6}
+}
+
+local total_ore_weights = {}
+local ore_t = 0
+for _, v in ipairs(ores) do
+    ore_t = ore_t + v.weight
+    table.insert(total_ore_weights, ore_t)
+end
+
+-- for the main islands. Cut down from original functionality. Hacky.
+local pattern = {}
+for r = 1, 50 do
+    local row = {}
+    pattern[r] = row
+    for c = 1, 50 do
+            row[c] = square
+    end
+end
+
+-- Make a 50 x 50 grid of ores with randomised ore types
+local random_ore = Random.new(ore_seed1, ore_seed2)
+local ore_pattern = {}
+for r = 1, 50 do
+    local row = {}
+    ore_pattern[r] = row
+    for c = 1, 50 do
+            local i = random_ore:next_int(1, ore_t)
+            local index = table.binary_search(total_ore_weights, i)
+            if (index < 0) then
+                index = bit32.bnot(index)
+            end
+            local ore_data = ores[index]
+
+            local ore_shape = ore_data.transform(small_ore_square)
+            local ore = b.resource(ore_shape, ore_data.resource, ore_data.value)
+
+            local shape = ore_square
+            shape = b.apply_entity(shape, ore)
+
+            row[c] = shape
+
+    end
+end
+
+-- create a mask to place over the ore grid
+local mask_square = b.rectangle(60,60)
+mask_square = b.change_tile(mask_square, true, 'sand-1')
+local mask_group = b.any{
+    mask_square,
+    b.translate(mask_square,90,0),
+    b.translate(mask_square,0,90),
+    b.translate(mask_square,90,90)
+}
+mask_group = b.translate(mask_group,-60,-60)
+
+-- sort out the starting ore patches
+local start_patch = b.scale(spider, 0.1, 0.1)
+local start_iron_patch =
+    b.resource(
+    b.translate(start_patch, 64, 0),
+    'iron-ore',
+    function()
+        return 5000
+    end
+)
+local start_copper_patch =
+    b.resource(
+    b.translate(start_patch, 0, -64),
+    'copper-ore',
+    function()
+        return 5000
+    end
+)
+local start_stone_patch =
+    b.resource(
+    b.translate(start_patch, -64, 0),
+    'stone',
+    function()
+        return 5000
+    end
+)
+local start_coal_patch =
+    b.resource(
+    b.translate(start_patch, 0, 64),
+    'coal',
+    function()
+        return 5000
+    end
+)
+
+local start_resources = b.any({start_iron_patch, start_copper_patch, start_stone_patch, start_coal_patch})
+local start = b.apply_entity(b.square_diamond(254), start_resources)
+
+-- Deathworld biters. Rawr!
+local worm_names = {'small-worm-turret', 'medium-worm-turret', 'big-worm-turret'}
+local spawner_names = {'biter-spawner', 'spitter-spawner'}
+local factor = 16 / (1024 * 32)
+local max_chance = 1 / 4
+
+local scale_factor = 4
+local sf = 1 / scale_factor
+local m = 1 / 600
+local function enemy(x, y, world)
+    local d = math.sqrt(world.x * world.x + world.y * world.y)
+    if d < 400 then
+        return nil
+    end
+
+    local threshold = 1 - d * m
+    threshold = math.max(threshold, 0.5) -- -0.125)
+
+    x, y = x * sf, y * sf
+    if Perlin.noise(x, y, enemy_seed) > threshold then
+        if math.random(8) <= 2 then
+            local lvl
+            if d < 300 then
+                lvl = 1
+            elseif d < 650 then
+                lvl = 2
+            else
+                lvl = 3
+            end
+
+            local chance = math.min(max_chance, d * factor)
+
+            if math.random() < chance then
+                local worm_id
+                if d > 1000 then
+                    local power = 1000 / d
+                    worm_id = math.ceil((math.random() ^ power) * lvl)
+                else
+                    worm_id = math.random(lvl)
+                end
+
+                return {name = worm_names[worm_id]}
+            end
+        else
+            local chance = math.min(max_chance, d * factor)
+            if math.random() < chance then
+                local spawner_id = math.random(2)
+                return {name = spawner_names[spawner_id]}
+            end
+        end
+    end
+end
+
+-- Put it all together
+local map = b.grid_pattern(pattern, 50, 50, 300, 300)
+map = b.choose(b.rectangle(300, 300), start, map)
+
+local resource_islands = b.grid_pattern(ore_pattern, 50, 50, 30, 30)
+resource_islands = b.change_tile(resource_islands, true, 'sand-1')
+
+local mask_pattern =
+{
+    {mask_group, mask_group, mask_group},
+    {mask_group, mask_group, mask_group},
+    {mask_group, mask_group, mask_group},
+}
+
+local resource_mask = b.grid_pattern(mask_pattern, 3, 3, 300, 300)
+resource_mask = b.translate(resource_mask,-130,-130)
+resource_islands = b.choose(resource_mask, resource_islands, b.empty_shape)
+
+local paths =
+    b.any {
+    b.single_y_pattern(h_track, 300),
+    b.single_x_pattern(v_track, 300)
+}
+
+local sea = b.tile('deepwater')
+sea = b.fish(sea, 0.0025)
+map = b.apply_entity(map, enemy)
+
+map = b.any {map, paths, resource_islands, sea}
+
+map = b.change_map_gen_collision_tile(map, 'water-tile', 'grass-1')
+
+
+
+
+local function on_init()
+
+    local surface = RS.get_surface()
+    local player_force = game.forces.player
+    local enemy_force = game.forces.enemy
+    player_force.technologies["landfill"].enabled = false -- disable landfill
+    --enemy_force.set_ammo_damage_modifier('melee', 1) -- +100% biter damage
+    enemy_force.set_ammo_damage_modifier('biological', 1) -- +100% spitter/worm damage
+    game.map_settings.enemy_expansion.enabled = true
+
+    -- Set up non-standard market so we can add logistics network things without editing a different file
+     Retailer.set_item('items', {price = 2, name = 'raw-fish'})
+     Retailer.set_item('items', {price = 1, name = 'rail'})
+     Retailer.set_item('items', {price = 2, name = 'rail-signal'})
+     Retailer.set_item('items', {price = 2, name = 'rail-chain-signal'})
+     Retailer.set_item('items', {price = 15, name = 'train-stop'})
+     Retailer.set_item('items', {price = 75, name = 'locomotive'})
+     Retailer.set_item('items', {price = 30, name = 'cargo-wagon'})
+     Retailer.set_item('items', {price = 15, name = 'steel-axe'})
+     Retailer.set_item('items', {price = 15, name = 'submachine-gun'})
+     Retailer.set_item('items', {price = 15, name = 'shotgun'})
+     Retailer.set_item('items', {price = 250, name = 'combat-shotgun'})
+     Retailer.set_item('items', {price = 25, name = 'railgun'})
+     Retailer.set_item('items', {price = 250, name = 'flamethrower'})
+     Retailer.set_item('items', {price = 175, name = 'rocket-launcher'})
+     Retailer.set_item('items', {price = 250, name = 'tank-cannon'})
+     Retailer.set_item('items', {price = 75, name = 'tank-flamethrower'})
+     Retailer.set_item('items', {price = 1, name = 'firearm-magazine'})
+     Retailer.set_item('items', {price = 5, name = 'piercing-rounds-magazine'})
+     Retailer.set_item('items', {price = 20, name = 'uranium-rounds-magazine'})
+     Retailer.set_item('items', {price = 2, name = 'shotgun-shell'})
+     Retailer.set_item('items', {price = 10, name = 'piercing-shotgun-shell'})
+     Retailer.set_item('items', {price = 5, name = 'railgun-dart'})
+     Retailer.set_item('items', {price = 25, name = 'flamethrower-ammo'})
+     Retailer.set_item('items', {price = 15, name = 'rocket'})
+     Retailer.set_item('items', {price = 25, name = 'explosive-rocket'})
+     Retailer.set_item('items', {price = 20, name = 'cannon-shell'})
+     Retailer.set_item('items', {price = 30, name = 'explosive-cannon-shell'})
+     Retailer.set_item('items', {price = 75, name = 'explosive-uranium-cannon-shell'})
+     Retailer.set_item('items', {price = 3, name = 'land-mine'})
+     Retailer.set_item('items', {price = 5, name = 'grenade'})
+     Retailer.set_item('items', {price = 35, name = 'cluster-grenade'})
+     Retailer.set_item('items', {price = 5, name = 'defender-capsule'})
+     Retailer.set_item('items', {price = 75, name = 'destroyer-capsule'})
+     Retailer.set_item('items', {price = 35, name = 'poison-capsule'})
+     Retailer.set_item('items', {price = 350, name = 'modular-armor'})
+     Retailer.set_item('items', {price = 875, name = 'power-armor'})
+     Retailer.set_item('items', {price = 40, name = 'solar-panel-equipment'})
+     Retailer.set_item('items', {price = 875, name = 'fusion-reactor-equipment'})
+     Retailer.set_item('items', {price = 100, name = 'battery-equipment'})
+     Retailer.set_item('items', {price = 625, name = 'battery-mk2-equipment'})
+     Retailer.set_item('items', {price = 250, name = 'belt-immunity-equipment'})
+     Retailer.set_item('items', {price = 100, name = 'night-vision-equipment'})
+     Retailer.set_item('items', {price = 150, name = 'exoskeleton-equipment'})
+     Retailer.set_item('items', {price = 250, name = 'personal-roboport-equipment'})
+     Retailer.set_item('items', {price = 10, name = 'construction-robot'})
+     Retailer.set_item('items', {price = 2, name = 'logistic-robot'})
+     Retailer.set_item('items', {price = 75, name = 'roboport'})
+     Retailer.set_item('items', {price = 50, name = 'logistic-chest-active-provider'})
+     Retailer.set_item('items', {price = 50, name = 'logistic-chest-passive-provider'})
+     Retailer.set_item('items', {price = 50, name = 'logistic-chest-requester'})
+     Retailer.set_item('items', {price = 50, name = 'logistic-chest-storage'})
+     Retailer.set_item('items', {price = 6, name = 'big-electric-pole'})
+     Retailer.set_item('items', {price = 3, name = 'medium-electric-pole'})
+     Retailer.set_item('items', {price = 50, name = 'substation'})
+
+     Retailer.set_market_group_label('items', 'Items Market')
+    local item_market_1 = surface.create_entity({name = 'market',  position={0,0}})
+    item_market_1.destructible = false
+    Retailer.add_market('items', item_market_1)
+
+
+end
+Event.on_init(on_init)
+
+return map
diff --git a/map_layout.lua b/map_layout.lua
index b81488ce..33795f79 100644
--- a/map_layout.lua
+++ b/map_layout.lua
@@ -87,6 +87,7 @@ local tiles_per_tick = 32
 --shape = require "map_gen.presets.christmas_tree_of_terror"
 --shape = require "map_gen.presets.rotten_apples"
 --shape = require "map_gen.presets.spiral_crossings"
+--shape = require "map_gen.presets.grid_bot_islands"
 --shape = require "map_gen.presets.test"
 
 --WIP maps--