Unlocking the variants is done through purchasing sticker packs from the Sticker Shop. The variants also differ slightly in appearance. *exact damage varies depending on distancemanaged to beat the plants by contacting his future self and bringing back advanced Z-Tech from the future, including the extremely powerful Z-Mech that gave the zombies the advantage over the plants. The zombies have taken over Suburbia and renamed it Zomburbia.
The zombies are "semi-mindless", decaying corpses that have won the Battle for Suburbia against the plants.