This game is amazing! But heres a suggestion though: Cake set. Cake hat (looks like a cake on top of your head)lets you double jump,
and you get it when you are rank 20. Cake body (looks like the normal body but sprinkled with cherries and icing) with is found on any random level with 2-4 players. Cake shoes (cupcake shoes!) is found the same as Cake body. But here is my review of the game:
Gameplay: 9/10. Great gameplay. It's kinda like mario kart, but 2D!
Graphics: 8/10. Great graphics though they are a bit chunky.
Diffulculty: 7/10.(based on campaign levels) Some are really hard, but most are really easy.
Overall: 8/10. Great, but with some little things that are bad.
I Have a way to get the achivement: Put the options the achivement says and go to the map boxy then shoot the barrels when the zombies come in and you should get fake walls and some other weapons and goodies.Put the fake walls up on the right side and shoot through one then the zombies will come in and use UZI or shotgun. Plus if this worked!