The official editor for Fallout 3, called the G.E.C.K. (Garden of Eden Creation Kit), will be available for free download in December and will allow Games for Windows® users to create and add their own content to the game.

"We've always seen the original world of Fallout 3 as a foundation for even more content. Some created by us, and a lot more created by users," said Todd Howard, game director for Fallout 3. "It's fun to create your own character, but it can be equally fun to create your own adventures. We can't wait to see what the community does with the G.E.C.K."

The release of the G.E.C.K. provides the community with tools that will allow players to expand the game any way they wish. Users can create, modify, and edit any data for use with Fallout 3, from building landscapes, towns, and locations to writing dialogue, creating characters, weapons, creatures, and more.​

Three downloadable content packs will be coming to Xbox 360 and Games for Windows Live starting in January that will add new quests, items, and content to Fallout 3.

• Operation: Anchorage. Enter a military simulation and fight in one of the greatest battles of the Fallout universe – the liberation of Anchorage, Alaska from its Chinese Communist invaders. An action-packed battle scheduled for release in January.
• The Pitt. Journey to the industrial raider town called The Pitt, located in the remains of Pittsburgh. Choose your side. Scheduled for release in February.
• Broken Steel. Join the ranks of the Brotherhood of Steel and rid the Capital Wasteland of the Enclave remnants once and for all. Continues the adventure past the main quest. Scheduled for release in March.