Zombie Evolution Pixel

Tap the tombs to get zombies. Drag a zombie to another identical one to merge them and evolve them to the next type of zombie. Each zombie can produce a specific number of brains per second. You can use the brains to buy new zombies and upgrade existing ones' production rates. There is the collection screen where you can check all the zombies you have unlocked. Challenge your friends to see who can collect the most kinds of zombie!