Pritty good
Now this game does get a little repetitive, but i have a suggestion for you to improve it. I played a game recently that you could buy weapons and kill things faster. now you could put in like the BFG10k from doom, I, II, or III, or the quake games. now you can put in any other types of weapons, and make the screen do weird things. Try to keep it from being repetitive, because that just gets borring. Other than that, you did very well, i know i couldn't do this sort of thing :-P .