New module

Whenever a character reaches its maximum inventory size the movement speed gets decreased.

maps/modules/burden.lua

@@ -0,0 +1,36 @@
+local event = require 'utils.event'
+local function compute_fullness(player)
+    local inv = player.get_inventory(defines.inventory.player_main)
+    local max_stacks = #inv
+    local num_stacks = 0
+
+    local contents = inv.get_contents()
+    for item, count in pairs(contents) do
+        local stack_size = 1
+        if game.item_prototypes[item].stackable then
+            stack_size = game.item_prototypes[item].stack_size
+        end
+
+        num_stacks = num_stacks + count / stack_size
+    end
+
+    return num_stacks / max_stacks
+end
+
+local function check_burden(event)
+    local player = game.players[event.player_index]
+    local fullness = compute_fullness(player)
+    player.character_running_speed_modifier = 0.5 - fullness
+end
+
+
+local function on_init(event)
+    script.on_event(defines.events.on_player_main_inventory_changed, check_burden)
+end
+
+local function on_load(event)
+    script.on_event(defines.events.on_player_main_inventory_changed, check_burden)
+end
+
+event.on_init(on_init)
+event.on_load(on_load)