interesting glitch that I could not be killed after getting invulnerability....
This game is so fun. I recommend also playing a game called Firefight which is like this only you're not killing zombies.
fun game but got boring once i unlocked the minigun. The bosses are pretty much the same to.
good game, although it can get laggy sometimes. i enjoyed it overall.
Tip: Upgrade the guns ammo first,Speed second and power last.