hmm, i like the concept, tho it kinda screams F.E.A.R, however who cares, i like the concept, gameplay seems acceptable, GUNplay seems bad though:

- gun sound effect [u have this]
- muzzle flash [your current one needs work]
- firing animation [work on this]
- tracer effect and speed/style of the tracer [alot of games tend to ignore this]
- enemy hit effect [need tweaks]
- enemy reaction upon hit [not a NEED]
- hit sound effect

your movement seems a bit too slow, maybe a sprint function