This could be really fun if it was a bit more fair on the player... Seems like Justice is being served in reverse!
Great looking visuals, I particularly like the lighting, although a little variation would be a nice touch. Also, having a slight delay before enemies shoot at you would also make it a bit more fair. Enemies spawn from the doors and before you have had time to aim your gun at their head, they have already got 4 shots into you.
And yes, where are the health pickups?? You take so much damage so easily and have no way (that I could find) to replenish your health.
Overall a very nice entry, just a few tweaks and it would be a very fun game!