Quite good
I'm generaly not a fan of "defence" type games, but this one is just too good.
I've played this game like, 5 times now, and everytime I'm bored, it still kills time like nothing else.
Only things to point out would be:
- The lack of maybe some "sound", more moans/grunts from the zombies or maybe a creepy Silent Hill-esq music on the background would add up.
- It's short... It is... It's very amusing, but it has the potential to go even further, maybe, as someone already mentioned, beeing able to suit up the other survivors or choose their placement. It would bring a new life to the game. Also, perhaps a "permanent" mode, where you'd have an infinite (or almost) ammount of incrisingly dificult levels, and the objective would be to see how long you'd survive.
That's pretty much it, I'll still be sure to play it again a lot. lol.