I can definitely vouch for this game, after playing it for the last few hours. Red showed me some basics that I was completely unaware of, and now will spread the glory with you all. You're spawned in a random location, throughout the world: sometimes near a town, military base, or neither. You can travel a distance to find one of these previously mentioned locations, where you will then find a horde of zombies, along with certain needed items, such as: food, weapons, drinks, and clothing. These items will allow you to progress your survival skills, and furthermore make you more prepared against the zombies (and players!
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When killing things, you get a gain +2 to 4 XP, where you can apply to your skills. To make yourself stronger, faster, or longer living without food; the decision is yours.
There are just a couple things this amazing, and free, game has to offer. I suggest you all try it out, and experience the fun yourself.