Exodus

You are in a single-screen shooter where your task is to prevent creatures and objects from escaping "The Pit," an octagonal prison. The escapees appear in the center and try to reach the edge. You move your spaceship around the perimeter and shoot inward to stop them, but you must avoid hitting your friend Spud, as doing so will cost you a life. An escapee only causes a life loss if it's a llama and reaches the edge. You also lose lives if you touch anything on the perimeter. A timer is also counting down, and if it reaches zero, the game ends, but you can shoot clocks to extend your time.