Simple and solid. I would have liked to see more variety like different weapons, upgrades, enemies movement/placement. It seemed there wasn't enough threat from enemies.

I would suggest adding a shop in the game so you can buy new weapons and stuff to kill your clones effectively XD

I love the gun. You feel powerful shooting that thing. Sound effects, screen shake, rapid/large bullets. It's great.

The gameplay itself seems to be missing a challenge. I stood still with the mouse down until the game started to lag from all the dead bodies.

The mechanics are very good though. At first it felt like a platformer and I still think maybe you could head that direction.

The gun feels great! I just wish there was a challenge to go along with it. A simple way to do this would be enemies that come from both sides, and maybe an enemy that can leap towards you, requiring you to dodge or aim your gun in another direction. Also, I'm not sure why you had intermissions where there's nothing to do but wait.

I planned to have enemies drop ammo, weapons, etc but I only had 72hrs (split between LD, Final Exams, and Final Projects)

The very basics are there, with movement and firing working nicely. All I did was stand in one place and mow them down while the framerate tanked though. :P