The official Fallout 3 mod tools have just been released for the PC version of Bethesda's shooter.
The Garden of Eden Creation Kit, or 'G.E.C.K.', lets you edit and create game content for Fallout, including your own towns and dungeons populated with your own characters, creatures, items and stories, says Bethesda.
The developers also launched a massive G.E.C.K. website full of tutorials, so there's no excuse for making rubbish dungeons if you're going to give it a go.