Last Fortress

Game description:

A world invaded by zombies is a grim and hopeless place. There is no space left for humans on the surface of our planet. Those who managed to survive without catching the virus are forced to live underground where they are still safe from the walking dead. To make sure the hungry monsters don’t get to you, you must build and fortify your underground home making it impenetrable for any attacks. Since you have to rise to the ground to find supplies, materials and ammo, be careful!