Doomsday Titans: The Invincible Fortress

When the apocalypse hits, Bill Trudy switches on a system known as the Doomsday Bunker, which he has been waiting to use. His only tool at the start is a welding torch, and it is the sole means he has to shield himself and whatever he can protect as the world falls apart. The opening moments set up a lone survivor who must build his defenses from almost nothing while the chaos outside grows worse.