Not bad...
For your first game, this is pretty good, but by the looks of it, people are going to blam it. Just wanted to tell you that I didn't think it was that bad. it's like whack-a-mole with blood and bullets! XD
Anyhow, you should seriously add some sound to this beast, and perhaps an ammo limit and a way to gain bullets and ammo. With those limitations and additions, it would be a pretty bitchin game. The guys should probably shoot back too. I don't know many people who stand by idly while you shoot them. Especially not guys who look like Brian Walsch (Head from KoRn) clones. All-in-all, good first try!