It feels like 2008 or so again. There's enough in the game with the unlockables and upgradables to make it not be too simple, and there was enough fun factor to make me play twice and try out other upgrade paths. It's got enough to be a 4/5 IMO. Maybe it would be better if there were more variety in the enemies' behavior since most of them just walk back and forth on the ground, and maybe if you had something like Kwing suggested and having something more like a target that the enemies reach to drop your HP, but personally I thought having enemies drain your HP when they're on the screen was fine. And I'm not getting any of the lag that fuckoffasshole had.