I've tried the game, and it seems like a solid start. You've implemented a jump, which ain't easy. It kind of shakes when you touch the ground, I don't know why. If you're having problems with anything, check out my project (that is if you can decipher which parts are for which).

You've got an AI, so that's further than me there. With some work you could turn this into a really good game (add some bullet holes though).

Also, make the guy a little faster, or add a sprint button or something. People aren't that patient.

I can imagine how could this could be if you put it into a good level, with good enemies and overall good GFX. Sorry I can't help there, but if you need any help scripting I'd be happy to help.