You Only Livez Twice a.k.a. YOLT is a game where you need to survive as a human against the zombie horde. The game has 7 levels in different environments such as a forest, a city, a farm and an old navy ship. The difficulty per level ranges from tutorial to nearly impossible. That doesn't have to be a problem by the way, because once you are eaten by the zombies you can just join their side and get the humans. You can complete the levels with an A-status as a human, or a B-status as a zombie.
WASD - move
Mouse - look
Click - shoot
You Only Livez Twice was created by Ben McMahan. He was the former lead creator of the well-known Google Doodles.