Develop.
Hehe, the people sounded funny when they died. :P
Well, i wouldnt say its REALLY bad, its a start. It runs semi-smooth. The motion from left to right needs to be smoother, and vice versa. The graphics isnt bad. Sometimes a bit, unresponsive if you know what i mean. If you developed more of the game, like add more enemies, or add some new weapons, it'll be great. Might even end up on my favourites. :P Umn...It'll be also better if you can see where YOUR kunai was going, because you don't see the kunai at all. Ya, add some music, and some other sound effects, like throwing sound effects or something. BG muisc etc etc.
Other than that, it was quite a smooth game, quite simple infact. Could use more work though.
Bascically, all you need is to develop more of the game, and it'll be great. ;D
7/10. :D Good Job.