The ammo counter and sound is good. How about making more subs appear over time? And then it could get more difficult by subs coming in more frequently...

Hm... I haven't thought of that. I was going to implement the levels with individually set up levels, but your idea of continuous leveling sounds much cooler and much more challenging ^^, Thanks for the idea delmar

Can you guys tell me how far you guys get in levels? I've tried making it as balanced as I can but I never tested past level 3 so that's uncharted territory XD Tell me if you find the end of the world. Also, any more suggestions? I still have to make the multiple submarine types, add more sounds, implement a constantly-changing background picture, and fix the Reset bug (you have to refresh the page if you want to reset the game >< ), but I feel like there's so much more that can be done...

Very nice! I got to level 7. Starts getting real fun there. The new submarines coming is very good, it also increases in difficulty quite well. I like the different speeds for the ship, too.

Are you using static fields for the ammo/level/score and the ships? That's not good - you cannot reset the game this way. After playing once, you cannot play again...