In the game, players get to choose between The Infected (whose types are strongly inspired, it seems, by Left 4 Dead) and The Survivors. On the Infected side, the player converts humans into special zombies, while trying to overrun the Survivors defenses. Meanwhile, the Survivors side is sort of a tower defense game.
A trailer for World Zombination has been released that shows off The Infected - a second one, which will focus on The Survivors, is due in the Fall 2013. Check it out in the video below.