diff --git a/main.tscn b/main.tscn
index a922d8c..733336b 100644
--- a/main.tscn
+++ b/main.tscn
@@ -1,66 +1,73 @@
-[gd_scene load_steps=12 format=3 uid="uid://cdaf4bh0jaa45"]
+[gd_scene load_steps=21 format=3 uid="uid://cdaf4bh0jaa45"]
 
-[ext_resource type="PackedScene" uid="uid://dq00mi6jwsa1f" path="res://scenes/planet/planet.tscn" id="1_0p552"]
-[ext_resource type="Script" path="res://scripts/game_logic.gd" id="1_kb05v"]
-[ext_resource type="Script" path="res://scenes/player/player.gd" id="2_plgh6"]
+[ext_resource type="Script" path="res://scripts/game_logic.gd" id="1_uj8ti"]
+[ext_resource type="Resource" uid="uid://cp0dudi0f5r62" path="res://scenes/templates/templates.tres" id="2_1lypt"]
+[ext_resource type="Script" path="res://scripts/player.gd" id="2_plgh6"]
 [ext_resource type="Texture2D" uid="uid://bydmcc5d53ldx" path="res://icons/paw_print.svg" id="3_mxakn"]
 [ext_resource type="Texture2D" uid="uid://1xh0qil16bkh" path="res://icons/character.svg" id="3_qxmev"]
-[ext_resource type="Script" path="res://scenes/player/local_player.gd" id="4_7rlmh"]
+[ext_resource type="Script" path="res://scripts/player_local.gd" id="4_7rlmh"]
 [ext_resource type="Texture2D" uid="uid://dx1wjviioa8u5" path="res://icons/chip.svg" id="4_pgo63"]
-[ext_resource type="Script" path="res://ui.gd" id="7_khbdl"]
-[ext_resource type="PackedScene" uid="uid://dtlatmtuggp6x" path="res://scenes/nebula/nebula.tscn" id="7_sv4lv"]
+[ext_resource type="Script" path="res://scripts/ui/planets_ui.gd" id="7_khbdl"]
+[ext_resource type="PackedScene" uid="uid://dtlatmtuggp6x" path="res://scenes/background_nebula/background_nebula.tscn" id="7_sv4lv"]
+[ext_resource type="Script" path="res://scripts/player_ai.gd" id="7_v73fw"]
+[ext_resource type="Script" path="res://scripts/planet.gd" id="8_ve3b1"]
 [ext_resource type="PackedScene" uid="uid://cpffyaoh8x5bp" path="res://scenes/ships_fleet/ships_fleet.tscn" id="9_be18b"]
 [ext_resource type="PackedScene" uid="uid://ckfk1xgxfk1c3" path="res://scenes/trail/trail.tscn" id="10_b5ql7"]
 
-[node name="Main" type="Node"]
-
-[node name="Logic" type="Node" parent="." node_paths=PackedStringArray("neutral_player", "players", "planets")]
-script = ExtResource("1_kb05v")
-neutral_player = NodePath("Players/0_Nature")
-players = [NodePath("Players/1_LocalPlayer"), NodePath("Players/2_AI")]
-planets = [NodePath("../Game/Planets/Planet1"), NodePath("../Game/Planets/Planet2"), NodePath("../Game/Planets/Planet3"), NodePath("../Game/Planets/Planet4")]
-
-[node name="Players" type="Node" parent="Logic"]
-
-[node name="0_Nature" type="Node" parent="Logic/Players"]
+[sub_resource type="Resource" id="Resource_mxp7y"]
 script = ExtResource("2_plgh6")
 color = Color(0.745, 0.745, 0.745, 1)
 icon = ExtResource("3_mxakn")
 
-[node name="1_LocalPlayer" type="Node" parent="Logic/Players" node_paths=PackedStringArray("ui")]
+[sub_resource type="Resource" id="Resource_1dtpf"]
 script = ExtResource("4_7rlmh")
-ui = NodePath("../../../UI")
-color = Color(0.184314, 0.329412, 1, 1)
+color = Color(0.236993, 0.373968, 1, 1)
 icon = ExtResource("3_qxmev")
 
-[node name="2_AI" type="Node" parent="Logic/Players"]
-script = ExtResource("2_plgh6")
+[sub_resource type="Resource" id="Resource_7wtc7"]
+script = ExtResource("7_v73fw")
 color = Color(0.835294, 0.160784, 0, 1)
 icon = ExtResource("4_pgo63")
 
-[node name="Nebula" parent="." instance=ExtResource("7_sv4lv")]
+[sub_resource type="Resource" id="Resource_50eg2"]
+script = ExtResource("8_ve3b1")
+location = Vector2(200, 200)
+type = 0
 
-[node name="Game" type="Node2D" parent="."]
+[sub_resource type="Resource" id="Resource_2525o"]
+script = ExtResource("8_ve3b1")
+location = Vector2(952, 448)
+type = 0
 
-[node name="Planets" type="Node2D" parent="Game"]
+[sub_resource type="Resource" id="Resource_irtww"]
+script = ExtResource("8_ve3b1")
+location = Vector2(450, 234)
+type = 0
 
-[node name="Planet1" parent="Game/Planets" instance=ExtResource("1_0p552")]
-position = Vector2(200, 200)
+[sub_resource type="Resource" id="Resource_wdycy"]
+script = ExtResource("8_ve3b1")
+location = Vector2(702, 414)
+type = 0
 
-[node name="Planet2" parent="Game/Planets" instance=ExtResource("1_0p552")]
-position = Vector2(952, 448)
+[node name="Main" type="Node"]
 
-[node name="Planet3" parent="Game/Planets" instance=ExtResource("1_0p552")]
-position = Vector2(450, 234)
+[node name="GameLogic" type="Node" parent="." node_paths=PackedStringArray("planets_container", "planets_ui")]
+script = ExtResource("1_uj8ti")
+templates = ExtResource("2_1lypt")
+planets_container = NodePath("../Planets")
+planets_ui = NodePath("../PlanetsUI")
+players = Array[ExtResource("2_plgh6")]([SubResource("Resource_mxp7y"), SubResource("Resource_1dtpf"), SubResource("Resource_7wtc7")])
+planets = Array[ExtResource("8_ve3b1")]([SubResource("Resource_50eg2"), SubResource("Resource_2525o"), SubResource("Resource_irtww"), SubResource("Resource_wdycy")])
 
-[node name="Planet4" parent="Game/Planets" instance=ExtResource("1_0p552")]
-position = Vector2(702, 414)
+[node name="BackgroundNebula" parent="." instance=ExtResource("7_sv4lv")]
+
+[node name="Planets" type="Node2D" parent="."]
 
 [node name="ShipsFleet" parent="." instance=ExtResource("9_be18b")]
 position = Vector2(246, 394)
 count = 29
 
-[node name="UI" type="Control" parent="." node_paths=PackedStringArray("trail")]
+[node name="PlanetsUI" type="Control" parent="." node_paths=PackedStringArray("trail")]
 layout_mode = 3
 anchors_preset = 15
 anchor_right = 1.0
@@ -71,5 +78,5 @@ mouse_filter = 2
 script = ExtResource("7_khbdl")
 trail = NodePath("Trail")
 
-[node name="Trail" parent="UI" instance=ExtResource("10_b5ql7")]
+[node name="Trail" parent="PlanetsUI" instance=ExtResource("10_b5ql7")]
 visible = false
diff --git a/scenes/nebula/nebula.gdshader b/scenes/background_nebula/background_nebula.gdshader
similarity index 100%
rename from scenes/nebula/nebula.gdshader
rename to scenes/background_nebula/background_nebula.gdshader
diff --git a/scenes/nebula/nebula.tscn b/scenes/background_nebula/background_nebula.tscn
similarity index 79%
rename from scenes/nebula/nebula.tscn
rename to scenes/background_nebula/background_nebula.tscn
index b48c073..1448855 100644
--- a/scenes/nebula/nebula.tscn
+++ b/scenes/background_nebula/background_nebula.tscn
@@ -1,6 +1,6 @@
 [gd_scene load_steps=5 format=3 uid="uid://dtlatmtuggp6x"]
 
-[ext_resource type="Shader" path="res://scenes/nebula/nebula.gdshader" id="1_nqp0c"]
+[ext_resource type="Shader" path="res://scenes/background_nebula/background_nebula.gdshader" id="1_nqp0c"]
 
 [sub_resource type="FastNoiseLite" id="FastNoiseLite_8c2xm"]
 
@@ -14,7 +14,7 @@ noise = SubResource("FastNoiseLite_8c2xm")
 shader = ExtResource("1_nqp0c")
 shader_parameter/noise = SubResource("NoiseTexture2D_cukca")
 
-[node name="Nebula" type="ColorRect"]
+[node name="BackgroundNebula" type="ColorRect"]
 material = SubResource("ShaderMaterial_y72ex")
 anchors_preset = 15
 anchor_right = 1.0
diff --git a/scenes/planet/planet.gd b/scenes/control_planet/control_planet.gd
similarity index 90%
rename from scenes/planet/planet.gd
rename to scenes/control_planet/control_planet.gd
index 7cdb576..3cda2e3 100644
--- a/scenes/planet/planet.gd
+++ b/scenes/control_planet/control_planet.gd
@@ -1,5 +1,5 @@
 extends Node2D
-class_name Planet
+class_name ControlPlanet
 
 ## The player currenly controlling this planet.
 var player: Player :
@@ -32,7 +32,7 @@ var is_selected: bool :
 	set(value):
 		%Selection.visible = value
 
-func _on_input_listener_input_event(viewport: Node, event: InputEvent, shape_idx: int) -> void:
+func _on_input_listener_input_event(_viewport: Node, event: InputEvent, _shape_idx: int) -> void:
 	# TODO: handle touch appropriately (InputEventScreenTouch).
 	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and event.is_pressed():
 		selected.emit(self)
diff --git a/scenes/planet/planet.tscn b/scenes/control_planet/control_planet.tscn
similarity index 92%
rename from scenes/planet/planet.tscn
rename to scenes/control_planet/control_planet.tscn
index c14cf48..a32b6ca 100644
--- a/scenes/planet/planet.tscn
+++ b/scenes/control_planet/control_planet.tscn
@@ -1,8 +1,8 @@
 [gd_scene load_steps=7 format=3 uid="uid://dq00mi6jwsa1f"]
 
 [ext_resource type="PackedScene" uid="uid://dnerbdusnaofr" path="res://scenes/procedural_planet/procedural_planet.tscn" id="1_8mf3x"]
-[ext_resource type="Script" path="res://scenes/planet/planet.gd" id="1_e208c"]
-[ext_resource type="Shader" path="res://scenes/planet/planet_selection.gdshader" id="2_bl05u"]
+[ext_resource type="Script" path="res://scenes/control_planet/control_planet.gd" id="1_e208c"]
+[ext_resource type="Shader" path="res://scenes/control_planet/planet_selection.gdshader" id="2_bl05u"]
 [ext_resource type="Texture2D" uid="uid://1xh0qil16bkh" path="res://icons/character.svg" id="2_kglxp"]
 
 [sub_resource type="CircleShape2D" id="CircleShape2D_tsywx"]
diff --git a/scenes/planet/planet_selection.gdshader b/scenes/control_planet/planet_selection.gdshader
similarity index 100%
rename from scenes/planet/planet_selection.gdshader
rename to scenes/control_planet/planet_selection.gdshader
diff --git a/scenes/player/local_player.gd b/scenes/player/local_player.gd
deleted file mode 100644
index ba145e7..0000000
--- a/scenes/player/local_player.gd
+++ /dev/null
@@ -1,10 +0,0 @@
-extends Player
-class_name LocalPlayer
-
-@export var ui: GameUI
-
-func _on_game_start(game: GameLogic) -> void:
-	ui._on_game_started(game)
-
-func _on_game_tick(game: GameLogic, tick: int) -> void:
-	pass
diff --git a/scenes/player/player.gd b/scenes/player/player.gd
deleted file mode 100644
index c866ed7..0000000
--- a/scenes/player/player.gd
+++ /dev/null
@@ -1,14 +0,0 @@
-extends Node
-class_name Player
-
-@export var color: Color = Color.MAGENTA
-
-@export var icon: Texture2D
-
-var pending_operations: Array[GameOperation] = []
-
-func _on_game_start(game: GameLogic) -> void:
-	pass
-
-func _on_game_tick(game: GameLogic, tick: int) -> void:
-	pass
diff --git a/scenes/ships_fleet/ships_fleet.gd b/scenes/ships_fleet/ships_fleet.gd
index 66588ef..60b9c32 100644
--- a/scenes/ships_fleet/ships_fleet.gd
+++ b/scenes/ships_fleet/ships_fleet.gd
@@ -1,22 +1,37 @@
 extends Node2D
+class_name ShipFleet
+
+@export var departed_at: int
+
+@export var arrives_at: int
+
+@export var from: Vector2
+
+@export var to: Vector2
+
+@export var count: int :
+	set(value):
+		count = value
+		_update_instances_count()
+
+#region Graphics
 
 var instances: Array[Node2D] = []
 
 @export var ship_template: PackedScene
 
-@export var count: int :
-	set(value):
-		count = value
+func _update_instances_count() -> void :
+	var diff = count - instances.size()
 
-		var diff = count - instances.size()
+	for i in range(diff):
+		var j = float(1 + instances.size())
+		var ship := ship_template.instantiate()
+		add_child(ship)
+		ship.position = Vector2.from_angle(j) * j * 2.
+		instances.push_back(ship)
 
-		for i in range(diff):
-			var j = float(1 + instances.size())
-			var ship := ship_template.instantiate()
-			add_child(ship)
-			ship.position = Vector2.from_angle(j) * j * 2.
-			instances.push_back(ship)
+	for i in range(-diff):
+		var ship: Node2D = instances.pop_back()
+		remove_child(ship)
 
-		for i in range(-diff):
-			var ship: Node2D = instances.pop_back()
-			remove_child(ship)
+#endregion
diff --git a/scenes/templates/template_scenes.gd b/scenes/templates/template_scenes.gd
new file mode 100644
index 0000000..4a64ddb
--- /dev/null
+++ b/scenes/templates/template_scenes.gd
@@ -0,0 +1,4 @@
+class_name TemplateScenes
+extends Resource
+
+@export var control_planet: PackedScene
diff --git a/scenes/templates/templates.tres b/scenes/templates/templates.tres
new file mode 100644
index 0000000..11026ef
--- /dev/null
+++ b/scenes/templates/templates.tres
@@ -0,0 +1,8 @@
+[gd_resource type="Resource" script_class="TemplateScenes" load_steps=3 format=3 uid="uid://cp0dudi0f5r62"]
+
+[ext_resource type="PackedScene" uid="uid://dq00mi6jwsa1f" path="res://scenes/control_planet/control_planet.tscn" id="1_3rbtf"]
+[ext_resource type="Script" path="res://scenes/templates/template_scenes.gd" id="1_yvn3m"]
+
+[resource]
+script = ExtResource("1_yvn3m")
+control_planet = ExtResource("1_3rbtf")
diff --git a/scripts/game_logic.gd b/scripts/game_logic.gd
index e6d109b..9cf36a7 100644
--- a/scripts/game_logic.gd
+++ b/scripts/game_logic.gd
@@ -1,69 +1,77 @@
-extends Node
 class_name GameLogic
+extends Node
 
-const LOGIC_TICKS_PER_SECOND: float = 20.
-const LOGIC_SECONDS_PER_TICK = 1. / LOGIC_TICKS_PER_SECOND
+const LOGIC_TICKS_PER_SECOND := 20.
+const LOGIC_SECONDS_PER_TICK := 1. / LOGIC_TICKS_PER_SECOND
 
-## Neutral player owning all non-conquered planets.
-@export var neutral_player: Player
+## Templates for spawnable stuff.
+@export var templates: TemplateScenes
+
+## Container for planets.
+@export var planets_container: Node2D
+
+## Interface to interact with planets.
+@export var planets_ui: PlanetsUI
 
 ## Game players.
-@export var players: Array[Player] = []
+@export var players: Array[Player]
 
 ## Game planets.
-@export var planets: Array[Planet] = []
+@export var planets: Array[Planet]
 
-var ticks_count: int
-var extra_time: float
+var _game: GameState
+var _planet_controls: Array[ControlPlanet]
 
-signal game_start(game: GameLogic)
-signal game_tick(game: GameLogic, tick: int)
+var _extra_time: float
 
 func _ready() -> void:
-	_game_init()
-	game_start.emit(self)
+	# New game.
+	_game = GameState.new()
+
+	# Add players.
+	for i in range(players.size()):
+		_game.add_player()
+
+	# Add planets.
+	for i in range(planets.size()):
+		# Data.
+		var data := GameState.PlanetData.new()
+		data.position = Vector2i(planets[i].location)
+		data.grow_every_ticks = 10
+		data.player_id = (i + 1) if (i < players.size() - 1) else 0
+		data.population = 0
+		_game.add_planet(data)
+
+		# UI control.
+		var control: ControlPlanet = templates.control_planet.instantiate()
+		control.position = planets[i].location
+		control.player = players[data.player_id]
+		control.population = data.population
+		_planet_controls.push_back(control)
+		planets_container.add_child(control)
+		planets_ui.register_planet(control)
+
+	# Register UI signals.
+	_game.planet_player_changed.connect(_set_planet_player)
+	_game.planet_population_changed.connect(_set_planet_population)
+	planets_ui.fleet_dispatched.connect(_dispatch_fleet)
 
 func _process(delta: float) -> void:
-	extra_time += delta
+	_extra_time += delta
 	
-	while extra_time > LOGIC_SECONDS_PER_TICK:
-		extra_time -= LOGIC_SECONDS_PER_TICK
-		_game_tick(ticks_count)
-		ticks_count += 1
+	while _extra_time > LOGIC_SECONDS_PER_TICK:
+		_extra_time -= LOGIC_SECONDS_PER_TICK
+		_game.tick()
 
-func _game_init() -> void:
-	ticks_count = 0
-	extra_time = 0.
+func _set_planet_player(planet_id: int, player_id: int) -> void:
+	_planet_controls[planet_id].player = players[player_id]
 
-	for player in players:
-		game_start.connect(player._on_game_start)
-		game_tick.connect(player._on_game_tick)
+func _set_planet_population(planet_id: int, population: int) -> void:
+	_planet_controls[planet_id].population = population
 
-	for i in range(planets.size()):
-		var planet := planets[i]
-		planet.player = players[i] if i < players.size() else neutral_player
-		planet.is_selected = false
-
-func _game_tick(tick: int) -> void:
-	for planet in planets:
-		if planet.player != neutral_player and tick % 10 == 0:
-			planet.population += 1
-
-	for player in players:
-		for op in player.pending_operations:
-			if op is GameOperationSendFleet:
-				var count = min(op.max_count, op.from.population)
-				op.from.population -= count
-				if op.from.player == op.to.player:
-					op.to.population += count
-				else:
-					op.to.population -= count
-					if op.to.population <= 0:
-						op.to.player = op.from.player
-						op.to.population = abs(op.from.population)
-			else:
-				assert(false, "Unknown GameOperation: %s" % [op])
-
-		player.pending_operations.clear()
-
-	game_tick.emit(self, tick)
+func _dispatch_fleet(from: ControlPlanet, to: ControlPlanet) -> void:
+	var player_id := players.find(from.player)
+	var from_planet_id := _planet_controls.find(from)
+	var to_planet_id := _planet_controls.find(to)
+	var max_count: int = ceil(from.population / 2.)
+	_game.dispatch_fleet(player_id, from_planet_id, to_planet_id, max_count)
diff --git a/scripts/game_operation.gd b/scripts/game_operation.gd
deleted file mode 100644
index 01f358d..0000000
--- a/scripts/game_operation.gd
+++ /dev/null
@@ -1,2 +0,0 @@
-extends RefCounted
-class_name GameOperation
diff --git a/scripts/game_operation_send_fleet.gd b/scripts/game_operation_send_fleet.gd
deleted file mode 100644
index acadd45..0000000
--- a/scripts/game_operation_send_fleet.gd
+++ /dev/null
@@ -1,8 +0,0 @@
-extends GameOperation
-class_name GameOperationSendFleet
-
-var from: Planet
-
-var to: Planet
-
-var max_count: int
diff --git a/scripts/game_state.gd b/scripts/game_state.gd
new file mode 100644
index 0000000..441e60d
--- /dev/null
+++ b/scripts/game_state.gd
@@ -0,0 +1,102 @@
+class_name GameState
+extends Resource
+
+class PlayerData:
+	var commands: Array[Command] = []
+
+class PlanetData:
+	var position: Vector2i
+	var grow_every_ticks: int
+	var player_id: int ## 0 = none
+	var population: int
+
+class FleetData:
+	var count: int
+
+enum CommandType {
+	DISPATCH_FLEET,
+}
+
+class Command:
+	var type: CommandType
+	var wait_tick: int
+
+class DispatchFleedCommand extends Command:
+	var from_planet_id: int
+	var to_planet_id: int
+	var max_count: int
+	func _init():
+		type = CommandType.DISPATCH_FLEET
+
+signal game_ticked(tick: int)
+signal planet_population_changed(planet_id: int, population: int)
+signal planet_player_changed(planet_id: int, player_id: int)
+
+var _players: Array[PlayerData] = []
+var _planets: Array[PlanetData] = []
+var _fleets: Array[FleetData] = []
+
+var current_tick: int
+
+## Add a player to the game.
+## The first player is expected to be the game master / neutral player,
+## who does not play and for whom the population never increases.
+func add_player(data := PlayerData.new()) -> int:
+	_players.push_back(data)
+	return _players.size() - 1
+
+## Add a planet to the game.
+func add_planet(data := PlanetData.new()) -> int:
+	_planets.push_back(data)
+	return _planets.size() - 1
+
+## Advance game status by one tick.
+func tick() -> void:
+	current_tick += 1
+
+	for planet_id in range(_planets.size()):
+		var planet := _planets[planet_id]
+		if planet.player_id != 0 and current_tick % planet.grow_every_ticks == 0:
+			planet.population += 1
+			planet_population_changed.emit(planet_id, planet.population)
+
+	for player_id in range(_players.size()):
+		var player := _players[player_id]
+		if player.commands.size() > 0 && current_tick >= player.commands[0].wait_tick:
+			var command: Command = player.commands.pop_back()
+			match command.type:
+				CommandType.DISPATCH_FLEET:
+					_handle_dispatch_fleet(player_id, command)
+				_:
+					assert(false, "Unknown command: %s" % [command])
+
+	game_ticked.emit(current_tick)
+
+## Dispatch a fleet.
+func dispatch_fleet(player_id: int, from_planet_id: int, to_planet_id: int, max_count: int) -> void:
+	var dispatch := DispatchFleedCommand.new()
+	dispatch.from_planet_id = from_planet_id
+	dispatch.to_planet_id = to_planet_id
+	dispatch.max_count = max_count
+	_issue_command(player_id, dispatch)
+
+func _issue_command(player_id: int, command: Command) -> void:
+	var commands := _players[player_id].commands
+	var index := commands.map(func (x): return x.wait_tick).bsearch(command.wait_tick, false)
+	commands.insert(index, command)
+
+func _handle_dispatch_fleet(player_id: int, dispatch: DispatchFleedCommand) -> void:
+	var from = _planets[dispatch.from_planet_id]
+	var to = _planets[dispatch.to_planet_id]
+	var count = min(dispatch.max_count, from.population)
+	from.population -= count
+	if from.player_id == to.player_id:
+		to.population += count
+	else:
+		to.population -= count
+		if to.population <= 0:
+			to.player_id = from.player_id
+			to.population = abs(from.population)
+			planet_player_changed.emit(dispatch.to_planet_id, to.player_id)
+	planet_population_changed.emit(dispatch.from_planet_id, from.population)
+	planet_population_changed.emit(dispatch.to_planet_id, to.population)
diff --git a/scripts/planet.gd b/scripts/planet.gd
new file mode 100644
index 0000000..401b673
--- /dev/null
+++ b/scripts/planet.gd
@@ -0,0 +1,10 @@
+class_name Planet
+extends Resource
+
+enum PlanetType {
+	TERRESTRIAL,
+}
+
+@export var location: Vector2
+
+@export var type: PlanetType
diff --git a/scripts/player.gd b/scripts/player.gd
new file mode 100644
index 0000000..b88b858
--- /dev/null
+++ b/scripts/player.gd
@@ -0,0 +1,9 @@
+class_name Player
+extends Resource
+
+@export var color: Color = Color.MAGENTA
+
+@export var icon: Texture2D
+
+func process_game_tick(_game: GameLogic) -> void:
+	pass
diff --git a/scripts/player_ai.gd b/scripts/player_ai.gd
new file mode 100644
index 0000000..b8504f2
--- /dev/null
+++ b/scripts/player_ai.gd
@@ -0,0 +1,5 @@
+class_name AIPlayer
+extends Player
+
+func process_game_tick(_game: GameLogic) -> void:
+	pass
diff --git a/scripts/player_local.gd b/scripts/player_local.gd
new file mode 100644
index 0000000..483d8d0
--- /dev/null
+++ b/scripts/player_local.gd
@@ -0,0 +1,5 @@
+class_name LocalPlayer
+extends Player
+
+func process_game_tick(_game: GameLogic) -> void:
+	pass
diff --git a/scripts/ui/planets_ui.gd b/scripts/ui/planets_ui.gd
new file mode 100644
index 0000000..2e3a300
--- /dev/null
+++ b/scripts/ui/planets_ui.gd
@@ -0,0 +1,80 @@
+class_name PlanetsUI
+extends Control
+
+@export var trail: Trail
+
+signal fleet_dispatched(from: ControlPlanet, to: ControlPlanet)
+
+func register_planet(control: ControlPlanet) -> void:
+	control.selected.connect(_on_planet_selected)
+	control.pointer_entered.connect(_on_planet_pointer_entered)
+	control.pointer_exited.connect(_on_planet_pointer_exited)
+
+func _process(delta: float) -> void:
+	_update_trail(delta, false)
+
+func _unhandled_input(event: InputEvent) -> void:
+	if event is InputEventMouse:
+		_handle_mouse_input(event)
+
+#region Mouse input
+
+var _last_cursor_position: Vector2
+
+func _handle_mouse_input(event: InputEventMouse) -> void:
+	if event is InputEventMouseMotion:
+		# The trail follows the cursor.
+		_last_cursor_position = event.global_position
+
+	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and event.is_released():
+		# The trail disappears when no longer dragging.
+		_dragging_from_planet = false
+		
+		# Detect mouse released on a planet and spawn a fleet.
+		if _selected_planet != null and _selected_planet.player is LocalPlayer and _pointed_planet != null:
+			fleet_dispatched.emit(_selected_planet, _pointed_planet)
+
+#endregion
+
+#region Planets
+
+var _selected_planet: ControlPlanet
+var _pointed_planet: ControlPlanet
+var _dragging_from_planet: bool
+
+func _on_planet_selected(planet: ControlPlanet) -> void:
+	if _selected_planet != null:
+		_selected_planet.is_selected = false
+
+	_selected_planet = planet
+	_selected_planet.is_selected = true
+
+	_dragging_from_planet = true
+	_update_trail(0., true)
+
+func _on_planet_pointer_entered(planet: ControlPlanet) -> void:
+	_pointed_planet = planet
+
+func _on_planet_pointer_exited(planet: ControlPlanet) -> void:
+	if _pointed_planet == planet:
+		_pointed_planet = null
+
+#endregion
+
+#region Trail
+
+var _trail_opacity := 0.
+
+func _update_trail(delta: float, snap_position: bool) -> void:
+	var show_trail := _dragging_from_planet and _selected_planet != null and _selected_planet.player is LocalPlayer
+	if show_trail or trail.visible:
+		_trail_opacity = Utils.damp(_trail_opacity, 1. if show_trail else 0., 1e-4, delta)
+		trail.color = Color(_selected_planet.player.color, _trail_opacity)
+		trail.visible = _trail_opacity > .01
+		
+		if show_trail:
+			var target_position = _last_cursor_position if _pointed_planet == null else _pointed_planet.global_position
+			trail.start_position = _selected_planet.global_position
+			trail.end_position = target_position if snap_position else Utils.damp(trail.end_position, target_position, 1e-20, delta)
+
+#endregion
diff --git a/scripts/util.gd b/scripts/utils.gd
similarity index 96%
rename from scripts/util.gd
rename to scripts/utils.gd
index f44479d..56a4ef9 100644
--- a/scripts/util.gd
+++ b/scripts/utils.gd
@@ -1,4 +1,4 @@
-class_name Util
+class_name Utils
 
 ## Time-independent damping with exponential-decay.
 ##
diff --git a/ui.gd b/ui.gd
deleted file mode 100644
index a5800c1..0000000
--- a/ui.gd
+++ /dev/null
@@ -1,88 +0,0 @@
-extends Control
-class_name GameUI
-
-@export var trail: Trail
-
-var game: GameLogic
-
-
-func _on_game_started(game: GameLogic) -> void:
-	self.game = game
-
-	for planet in game.planets:
-		planet.selected.connect(_on_planet_selected)
-		planet.pointer_entered.connect(_on_planet_pointer_entered)
-		planet.pointer_exited.connect(_on_planet_pointer_exited)
-
-func _process(delta: float) -> void:
-	_update_trail(delta, false)
-
-func _unhandled_input(event: InputEvent) -> void:
-	if event is InputEventMouse:
-		_handle_mouse_input(event)
-
-#region Mouse input
-
-var last_cursor_position: Vector2
-
-func _handle_mouse_input(event: InputEventMouse) -> void:
-	if event is InputEventMouseMotion:
-		# The trail follows the cursor.
-		last_cursor_position = event.global_position
-
-	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and event.is_released():
-		# The trail disappears when no longer dragging.
-		dragging_from_planet = false
-		
-		# Detect mouse released on a planet and spawn a fleet.
-		if selected_planet != null and selected_planet.player is LocalPlayer and pointed_planet != null:
-			var op := GameOperationSendFleet.new()
-			op.from = selected_planet
-			op.to = pointed_planet
-			op.max_count = ceil(selected_planet.population / 2)
-			selected_planet.player.pending_operations.push_front(op)
-
-#endregion
-
-#region Planets
-
-var selected_planet: Planet
-var pointed_planet: Planet
-var dragging_from_planet: bool
-
-func _on_planet_selected(planet: Planet) -> void:
-	if selected_planet != null:
-		selected_planet.is_selected = false
-
-	selected_planet = planet
-	selected_planet.is_selected = true
-
-	dragging_from_planet = true
-	_update_trail(0., true)
-
-func _on_planet_pointer_entered(planet: Planet) -> void:
-	pointed_planet = planet
-
-func _on_planet_pointer_exited(planet: Planet) -> void:
-	if pointed_planet == planet:
-		pointed_planet = null
-
-#endregion
-
-#region Trail
-
-var trail_opacity := 0.
-
-func _update_trail(delta: float, snap_position: bool) -> void:
-	var show_trail := dragging_from_planet and selected_planet != null and selected_planet.player is LocalPlayer
-	if show_trail or trail.visible:
-		trail_opacity = Util.damp(trail_opacity, 1. if show_trail else 0., 1e-4, delta)
-		trail.color = Color(selected_planet.player.color, trail_opacity)
-		trail.visible = trail_opacity > .01
-		
-		if show_trail:
-			var target_position = last_cursor_position if pointed_planet == null else pointed_planet.global_position
-			trail.start_position = selected_planet.global_position
-			trail.end_position = target_position if snap_position else Util.damp(trail.end_position, target_position, 1e-20, delta)
-
-#endregion