A massive demonic invasion has overwhelmed the Union Aerospace Corporation's (UAC) Mars Research Facility, leaving only chaos and horror in its wake. As one of only a few survivors, you must fight your way to hell and back against a horde of evil monsters. The path is dark and dangerous, but you'll have an array of weapons--including a pistol, a chainsaw, grenades, and more--to use for protection.
1. Download, install and run installer STEAM.
2. After the game run, create your STEAM account according to instructions on screen, after that go into tab Games, options for product activation on Steam, copy the game bought game key from your KeenShop account
3. After this procedure the game and it's parts is present at Games tab.