diff --git a/project.godot b/project.godot
index 90203d7..cdc3a8a 100644
--- a/project.godot
+++ b/project.godot
@@ -19,10 +19,6 @@ config/icon="res://icon.svg"
 
 gdscript/warnings/untyped_declaration=1
 
-[display]
-
-window/size/always_on_top=true
-
 [gui]
 
 theme/custom="res://data/world_theme.tres"
diff --git a/scripts/Base.gd b/scripts/Base.gd
index 8393bd6..232afbf 100644
--- a/scripts/Base.gd
+++ b/scripts/Base.gd
@@ -1,10 +1,12 @@
 extends Node2D
 class_name Base
 
+@export var corruption_pattern: ExpansionBase
 @export var world: World
+
+@onready var expand_timer: Timer = $ExpandTimer
 var grid_loc: Vector2i
 
-const curruption_directions := [Vector2i.LEFT, Vector2i.RIGHT, Vector2i.UP, Vector2i.DOWN]
 var corruption_tiles: Array[Vector2i] = []
 
 func _ready() -> void:
@@ -14,8 +16,10 @@ func _ready() -> void:
 	world.corrupt_location(grid_loc)
 
 func _on_expand_timer_timeout() -> void:
-	var corrupt_tile: Vector2i = corruption_tiles.pick_random() + self.curruption_directions.pick_random()
-	while corruption_tiles.has(corrupt_tile):
-		corrupt_tile = corruption_tiles.pick_random() + self.curruption_directions.pick_random()
-	corruption_tiles.append(corrupt_tile)
-	world.corrupt_location(corrupt_tile)
+	var corrupt_tile: Vector2i = corruption_pattern.expand_next_tile() + grid_loc
+	if corrupt_tile:
+		corruption_tiles.append(corrupt_tile)
+		world.corrupt_location(corrupt_tile)
+
+func on_corruption_finished() -> void:
+	expand_timer.stop()
diff --git a/scripts/building_manager.gd b/scripts/building_manager.gd
index d2e7221..9fd6035 100644
--- a/scripts/building_manager.gd
+++ b/scripts/building_manager.gd
@@ -5,8 +5,10 @@ var base = preload("res://scene/base.tscn")
 
 func _unhandled_input(event):
 	if event is InputEventMouseButton and event.is_pressed() and event.button_index == MOUSE_BUTTON_LEFT:
-		var build = base.instantiate()
+		var build: Base = base.instantiate()
 		build.position = get_global_mouse_position()
 		build.world = world
+		build.corruption_pattern = ExpansionSquarePattern.new()
+		build.corruption_pattern.expansion_finished.connect(build.on_corruption_finished)
 		add_child(build)
 		#world_grid.set_cell(2, world_grid.local_to_map(get_global_mouse_position()), 0, Vector2i(16,2))
diff --git a/scripts/expansion_patterns/expansion_base.gd b/scripts/expansion_patterns/expansion_base.gd
new file mode 100644
index 0000000..5c25e5a
--- /dev/null
+++ b/scripts/expansion_patterns/expansion_base.gd
@@ -0,0 +1,6 @@
+class_name ExpansionBase extends Resource
+
+signal expansion_finished
+
+func expand_next_tile() -> Vector2i:
+	return Vector2i.ZERO
diff --git a/scripts/expansion_patterns/expansion_square_pattern.gd b/scripts/expansion_patterns/expansion_square_pattern.gd
new file mode 100644
index 0000000..c08f0e1
--- /dev/null
+++ b/scripts/expansion_patterns/expansion_square_pattern.gd
@@ -0,0 +1,19 @@
+class_name ExpansionSquarePattern extends ExpansionBase
+
+const EXPANSION_STAGES: int = 3
+
+var expansion_stage: int = 0
+var expansion_tiles: Array[Vector2i] = []
+
+func expand_next_tile() -> Vector2i:
+	if expansion_tiles.is_empty():
+		if expansion_stage < EXPANSION_STAGES:
+			expansion_stage += 1
+			for x in range(-expansion_stage, expansion_stage + 1):
+				for y in range(-expansion_stage, expansion_stage + 1):
+					if abs(x) == expansion_stage or abs(y) == expansion_stage:
+						expansion_tiles.append(Vector2i(x, y))
+	if expansion_stage == EXPANSION_STAGES and expansion_tiles.size() == 1:
+		expansion_finished.emit()
+	
+	return expansion_tiles.pop_at(randi_range(0, expansion_tiles.size() - 1))
diff --git a/scripts/gui.gd b/scripts/gui.gd
index 1a153a6..9d996f2 100644
--- a/scripts/gui.gd
+++ b/scripts/gui.gd
@@ -1,6 +1,6 @@
 extends Control
 
-@onready var resource_container: GridContainer = $ResourceContainer/VBoxContainer/GridContainer
+@onready var resource_container: GridContainer = $ResourceContainer/MarginContainer/VBoxContainer/GridContainer
 const SCIFI_TILESHEET = preload("res://assets/scifi_tilesheet@2.png")