Dead Island

http://store.steampowered.com/app/91600/

A great game to play with friends, not so good by yourself or with strangers but still playable. It's a lot of fun and the landscapes have a nice variety to keep it feeling fresh. As you play the zombies you face become harder but I didn't feel overwhelmed by the amount of them at any point in the game, it could stand to be a bit more challenging. There's a few secrets in the game and a lot of thought was put into the co-op mode. The game contains vehicles and suprisingly they aren't awful to control, they actually handle pretty decently. I really enjoyed playing through this game with my friends and highly recommend it if you have someone to play with.