submarine

Nice start :) After a while though I was playing and got the following error: java.lang.IllegalStateException: The actor has not been inserted into a world so it has no location yet. You might want to look at the method addedToWorld on the Actor class. at greenfoot.Actor.failIfNotInWorld(Actor.java:604) at greenfoot.Actor.getX(Actor.java:136) at sub.missileAttack(sub.java:56) at sub.act(sub.java:30) at greenfoot.core.Simulation.runOneLoop(Simulation.java:200) at greenfoot.core.Simulation.run(Simulation.java:129) ...so you might want to look and see if there's anything wrong with that line. In terms of other suggestions, what about speeding up gradually instead of suddenly every so often, and perhaps more bullets too? I found it quite easy as it is.