Kalmo is a zombie RPG designed by Risto J. Hieta and it was part of his Arctic Ranger Productions series of small RPGs in the beginning of 2000's. It was the most popular game of the series and has been reprinted several times with slight improvements to the rules.
Unlike in most zombie-RPGs, in Kalmo the players play the zombies, not the humans trying to survive a zombie attack. Each player gets a single, dumb zombie recently risen to undead-hood. The idea is to survive as a zombie in the normal world, which doesn't understand zombies and is usually quite hostile towards them.
The game does not take itself too seriously, but it is actually a very playable game. First edition used d8 but third edition moved to d12, because d12 dice don't sell that well otherwise.