Playtesting
If only you did it, it would be great.
While everything else is fine, I just have the same gripes as everyone else, like the fact that you stop shooting when you get hit, glitchy machine gun, slow nades, crap shotgun, etc. etc.
However, I would've liked a more linear game, or at least a running option or something, because I hate backtracking. The sound's a little icky to me too.