Doom Zombie Survival is a tough first-person shooter game that takes place in a world overrun by zombies after the end of the world.
In each level, you move from one room to another or other places and are put in front of a group of zombies that slowly move toward you. You have to shoot them down before they reach you, or they will eat your brains and you will die.
Use the left mouse button to shoot and the right mouse button to move the scope. As you complete levels and move on to the next one, you'll be able to get new guns and weapons that are more powerful against the undead enemies, who also get stronger and more numerous.
Have fun and good luck!