i confirm java heap space problem, solved as dkson suggested!
I suggest to you use of
Launch4j, to make a simple exe
game i coool!
You need to build a webstart and an applet, so this game can be really a time killer
my 2 cents:
- you need more "light" package . 9mb for this game is too much

maybe you can use more compressed images?
- i see a scala library on your package (3mb!!): are you using scala to build this game? how is to use it?
- i like graphics
- maybe some strange pieces, like time-freeze, laser beam, or some strange ideas?
as you said, you need an online highscore, some other modes (time trial?).. but good work
