The mod toolset, dubbed G.E.C.K. (Garden of Eden Creation Kit), will arrive as a free download for PC users in December. "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," wrote Bethesda.

Three pieces of game-expanding downloadable content were announced for PC and Xbox 360 users, set to arrive on a monthly basis beginning in January. No price point was specified, though Bethesda offered the following descriptions:

• 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.

Launched October 28 on PC, PlayStation 3 and Xbox 360, the post-apocalyptic RPG shipped 4.7 million units and brought in over $300 million during its first week at retail. In addition to the DLC, Bethesda is currently working on a patch.