Earth is not the place that you used to know... Aliens invaded and changed our planet overnight. Most terrans have already been wiped off the planet, the ecosystem has been altered to suit the needs of the aliens, and even the air has been modified and it became poisonous for humans and animals. Few humans survived but they're hiding in underground shelters, and their fight seems to be a hopeless one. Desperate needs call for desperate measures, which could bring even more destruction! Make it to the safe house in one piece, look for supplies and survivors on the way and try to find out what is going on. Working together with comrades is a must!
Use Arrow keys to move and aim, Space bar to interact or throw enemies, A to shoot, S to jump (double tap for double jump), R to reload, Q to switch weapons, E to eat food rations. Follow the in-game instructions that will help you a lot.