Are you afraid of a darkness? Well, imagine a situation that you barely see few centimetres in front of you, add weird sounds, and that is it. Then, when you spot first zombie, you realize that this was not a joke. Run as fast as you can, avoid any contact with zombies, and hope that you will somehow survive. Use various perks like armor vest or head start to boost your runs, and try to get as far as possible before you get killed. The further you run, the more money you get. As you progress through the game, unlock more weapons, use them to your advantage, and set the new best distance. Have fun.