I love this game but it really needs a restart button!! I can tell from the first attempt if I'm going to fail on the hard badge, refresh takes too long.
This game is awesome. I think it would be great however if there was a kamikaze option! I mean, your in the later waves, your getting completely swamped with zombies, you have used your last medi kit and down to a pathetic amount of health.... Boom! Take some undead with you and gain some bonus exp points. That would be very satisfying :D