The $2.99 Z0MB1ES!!1 (on teh ph0ne) app is a "suite" of twin-stick shooters, which includes I MAED A GAEM W1TH Z0MB1ES 1N IT!!1, "spiritual sequel" Time Viking, infinite arcade labyrinth mod Endless Zombies and the ability to put faces from your photo library into the game.
Getting the Z0MB1ES!!1theme song stuck in your head comes at no extra cost.