They thought that they are save because they are already in the helicopter. Unfortunately, they didn't notice that one of them got bitten. Soon, the trouble starts again as the bitten suddenly turned into the undead and start attacking them. There copter fell and now, all is left is you as you fight the zombie hordes. Gathering everything that you can find and building a barricade, you are able to hold them off for some time. But, you know that you need to move out and move in to Union city as the government will soon move out. When that happens, there is no chance for you to live.
The game is played via mouse and keyboard. The idea here is to survive the horse of zombies attacking your barricade. Try to shoot every last bit of them. Don't let them get close to the barricade. After an attack, you can search for survivors, weapon and supplies. You can also repair the barricade. All of the said activities need time. You have 12 hours to do all of that. If you manage to survive a few times then you can head on to another city or town, where you can build a barricade.