Good... but laggy.
It's a good game with great features. However, once you get far enough into the game, the lag starts becoming an ENORMOUS issue. It is REALLY hard to play a game at 2 frames per second.
I'll give you major props on the weapon and upgrade design, as it kept me playing for a long while. The enemies should probably get better weapons further in though, because once you have all the upgrades, you just can't die ( especially if you have the railgun <3 ).
I really really really REALLY wanted to give this game a good score, but the lag is a major downer; in fact, it made me close down the game.