Go into the Java control panel, navigate to the advanced tab and make sure either show console or hide console is checked (as long as it's not never show console.) Also make sure you have the option set to get the java coffee icon in your taskbar when a java application launches. If you selected show console it'll open automatically (which I find dead annoying.) If you selected hide console then just right click on the icon and select show console when you want to see it (if the simulation stops suddenly when you don't expect it to, that's usually a good sign that an error's occured.)

Much better movement, I don't get stuck any more! However, I'm still a bit lost as to where I need to go, is there some kind of end to the maze? Some instructions would be good as well.

One way to solve the overlapping problem would be to either expand the world a bit or shrink the number of enemies, and then code it so that when one enemy hits the edge of the screen, they all change direction together (rather than individually.) Depending on your implementation, this could be as simple as changing the world's co-ordinates and making a variable static :-)

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.

Did you change the title? That might've been what confused it. Nice preset formations! Only thing that I'm noticing now is that some of the dominoes (in the middle row of the default formation) seem to fall instantaneously rather than gradually... good apart from that though!

Ooh :-) I've no idea what's actually happening, but it looks cool!

Nice start with this one, a good first game! As spaceblue said the thing that I'd implement next would be some sort of delay so you can't fire bullets continuously. Good work so far though!