It's fun, but later on it gets really laggy and I can't save myself from death because I don't get a chance to open the shop window and buy a health pack before the zombies kill me.
I keep getting stuck in the place where there's a yellow laser but nothing to turn it off. The time it takes to get to there from the thing that turns it off is such that it turns off when I'm on it and I get stuck.
Ahhh, but you see, that's on purpose. Notice the "i" in the title, now notice the shape of the characters in-game... WOAH