First part is good, second part is terrible
I love the concept of the game, and I think it's awesome that you were able to make a single player campaign, but I think it gets to be impossible at level 21. I've noticed that I can hit the enemy multiple times with the particle gun or the rocket launcher without getting a kill, but the enemy can mow people down with pistols. Also, in terms of accuracy, I've been killed by enemies as they're flipping through the air and shooting with the sniper rifle. The whole game basically becomes impossible after this point.
I've also seen a couple of glitches, the most egregious of which are:
1. If you use up a magazine and switch weapons instead of reloading, that gun becomes unusable until you get killed, even if you have more ammo for it.
2. I've occasionally felt like I have shot an enemy while he was flipping and the shot did not register. Seems worse for sniper and particle guns.
Other than the above, it's a great game and worthy of a multiplayer mode, but only after these things are fixed.