Zombie Crisis (The Original)
Zombie Crisis is a stand-alone game for the PSP and PC platforms. The game sticks with a simple pattern through all of its six levels: you move, you push a few buttons and you kill. There are no secret places, no alternative routes, no keys, no spritework, no special effects - nothing but you & tons of zombies. This keeps the mod simple and fun, for a while, but it also makes you expect more.