     fire_bullets(game)
     check_for_collisions(game)
 
-    {:reply, 
-      {:elapsed_ms, elapsed_ms}, 
-      Map.put(game, :clock_ms, Clock.now_ms)}
+    new_game = game
+    |> maybe_spawn_asteroid
+    |> update_game_clock
+
+    {:reply, {:elapsed_ms, elapsed_ms}, new_game}
   end
 
   def handle_call(:state, _from, game) do

    put_in(game.pids.asteroids[id], pid)
  end

  # Development

  defp fire_bullets(game) do

  alias World.Clock, as: Clock
  alias Game.Collision, as: Collision

  @initial_asteroid_count    1
  @initial_ship_count       16

  def start_link(fps \\ 0) do
