Good job!
Pretty creative. I like the sound bytes.
Just a thought... Selectively speeding up the the playback rate in spots might add interest by making it seem even more video-game like, as well as keeping the action moving quickly. The part where the shotgun is fetched from the corpse stands out. In real life, it takes a few seconds to kneel down, take the weapons, etc. It's a relatively boring action that might be funny if turn it into a benny-hill-like sequence.
You could also slow down playback for a matrix like effects. Anyway, that's my two-bits.
Good job!