feat: Implement Stop N Go game mode with a new manager script and associated gridmap assets within the MeshLibrary.

scripts/managers/stop_n_go_manager.gd

@@ -22,7 +22,8 @@ var finish_line_x: int = 21 # Right side of the map for win condition
 
 # Tile IDs
 const TILE_WALKABLE = 0
-const TILE_START = 2 # Start Line
+const TILE_START = 3 # Start Line
+const TILE_FINISH = 3 # Finish Line
 const TILE_SAFE = 2 # Green Safe Zone
 const TILE_OBSTACLE = 4 # Wall
 
@@ -143,7 +144,7 @@ func _update_stop_timer_visuals():
 				var hbox = stop_timer_node.get_node_or_null("HBox")
 				if hbox:
 					stop_segments.clear()
-					for i in range(4):
+					for i in range(3):
 						var seg = hbox.get_node_or_null("Segment%d" % i)
 						if seg: stop_segments.append(seg)
 				
@@ -173,9 +174,9 @@ func _update_stop_timer_visuals():
 	stop_timer_node.visible = true
 
 	if current_phase == Phase.GO:
-		# GO Phase: All dim unless in last 4 seconds
+		# GO Phase: All dim unless in last 3 seconds
 		for i in range(stop_segments.size()):
-			var threshold = 4.0 - i
+			var threshold = 3.0 - i
 			if phase_timer <= threshold:
 				stop_segments[i].add_theme_stylebox_override("panel", lit_style)
 			else:
@@ -277,6 +278,8 @@ func _apply_arena_setup():
 		var tile_id = TILE_WALKABLE
 		if x == 0:
 			tile_id = TILE_START
+		elif x == gridmap.columns - 1:
+			tile_id = TILE_FINISH
 		elif x in safe_columns:
 			tile_id = TILE_SAFE
 		
@@ -352,16 +355,14 @@ func _spawn_mission_tiles():
 			if base_tile == TILE_OBSTACLE:
 				continue
 				
-			# Randomly populate other floors with goal tiles
-			# 30% chance to have a tile to avoid overcrowding
-			if randf() < 0.3:
-				var tile_type = goal_items[randi() % goal_items.size()]
-				gridmap.set_cell_item(Vector3i(x, 1, z), tile_type)
-				
-				# Sync to clients
-				var main = get_node("/root/Main")
-				if main:
-					main.rpc("sync_grid_item", x, 1, z, tile_type)
+			# Spawn tiles on all floors (100% density)
+			var tile_type = goal_items[randi() % goal_items.size()]
+			gridmap.set_cell_item(Vector3i(x, 1, z), tile_type)
+			
+			# Sync to clients
+			var main = get_node("/root/Main")
+			if main:
+				main.rpc("sync_grid_item", x, 1, z, tile_type)
 
 func _assign_missions():
 	# NO-OP: Missions are now achievement-based (Complete 3 Goals)
@@ -384,7 +385,7 @@ func check_movement_violation(player_id: int, from: Vector2i, to: Vector2i) -> b
 			# Usually implies checking if you ARE in a safe zone.
 			var tile_from = gridmap.get_cell_item(Vector3i(from.x, 0, from.y))
 			
-			if tile_from != TILE_SAFE:
+			if tile_from != TILE_SAFE and tile_from != TILE_START and tile_from != TILE_FINISH:
 				_penalize_player(player_id)
 				return true
 	return false