General idea was good, and I enjoyed the part where he fought his hallucination near the equipment locker. I feel like you could do well to expand on that premise in any continuation.
It's clear that a lot of effort was put into this, and the combat isn't that bad. Most points here are going for the general premise, and a few interesting effects.
You missed out a lot of details that could have made this better, little things that would have appealed to me. For example, when he kills the bandage-wearing agent, the agent flips him off. I would have liked it better if you did a little more with that, perhaps having the main character cutting off the finger in a kind of Grindhouse style moment.