Joystiq offers a very nice bullet-pointed set of features in Fallout 3. Check it out:
The game takes place 30 years after the events Fallout 2. The events of the much-maligned Fallout: Brotherhood and Fallout: Tactics never happened in the universe of Fallout 3.
The game will feature a day/night cycle and changing weather.
There will be 21 collectible bobbleheads hidden throughout the game for Easter egg lovers.
The
game will feature 20 licensed songs from the '40s that will be played
through radio stations accessible via your on-arm PIP-Boy and radios
peppered throughout the game world.
There will be no drivable vehicles in the game, but you can travel between locations through subway tunnels.
There are children in the game, but the team isn't sure yet if they will be killable as they were in the previous Fallout games.
The game will have no multiplayer mode and no demo is currently planned.
Downloadable content and player-created mods are being considered, but nothing has been finalized.
The game will feature nine to 12 endings based on how you've played it.
The
game's version of Washington D.C. will include iconic landmarks and the
general topography of the real city, but will not be a street-by-street
recreation. The downtown area represents about one quarter of the
in-game map.
There will be fewer non-player characters in Fallout 3 than in Oblivion, owing to the game's post-apocalyptic setting. Almost all the NPCs will be killable.
You'll be able to hire mercenaries to aid you as in the first Fallout game. You won't have much direct control over them.
Among
other statistics, the demo's loading screens contained a mysterious
metric of "corpses eaten." "We're not talking about that stuff,"
Executive Producer Todd Howard said when asked about the stat.