Full list of all 72 Fallout 3 achievements worth 1,550 gamerscore. It takes around 60-80 hours to unlock all of the achievements in the base game on Xbox 360.
The base game contains 50 achievements worth 1,000 Gamerscore, and there are 5 DLC packs containing 22 achievements worth 550 Gamerscore.
All achievements
Achievements they've won
Achievements they've not won
Completed "You Gotta Shoot 'Em in the Head"
Completed "Head of State"
Completed "Take it Back!"
Reached Level 20 with Good Karma
Completed "The American Dream"
Collected 10 Vault-Tec Bobbleheads
Completed "Oasis"
Picked 50 locks
Completed "Big Trouble in Big Town"
Completed "Those!"
Completed "The Nuka-Cola Challenge"
Completed "Agatha's Song"
Killed 300 creatures
Completed "Reilly's Rangers"
Completed "Stealing Independence"
Completed "The Superhuman Gambit"
Completed "Trouble on the Homefront"
Completed "Tenpenny Tower"
Placed a grenade or mine while pickpocketing
Reached Level 14 with Good Karma
Completed "Finding the Garden of Eden"
Completed "Picking up the Trail"
Completed "Galaxy News Radio"
Completed "Rescue from Paradise"
Completed "The Waters of Life"
Reached Level 8 with Good Karma
Completed "The Replicated Man"
Completed "Tranquility Lane"
Completed "Scientific Pursuits"
Completed "The Wasteland Survival Guide"
Completed "The Power of the Atom"
Completed "Blood Ties"
Completed "Following in His Footsteps"
Completed "Escape!"
Took the G.O.A.T.
Got the Pip-Boy 3000
Completed "Strictly Business"
Reached Level 8 with Bad Karma
Reached Level 8 with Neutral Karma
Reached Level 14 with Bad Karma
Reached Level 14 with Neutral Karma
Reached Level 20 with Bad Karma
Reached Level 20 with Neutral Karma
Made one of every custom weapon
Killed 300 people
Won 50 Speech Challenges
Hacked 50 terminals
Discovered 100 locations
Kill all the Super Mutant Behemoths
Collected 20 Vault-Tec Bobbleheads
Completed "Aiding the Outcasts"
Completed "The Guns of Anchorage"
Completed "Paving the Way"
Completed "Operation: Anchorage"
Completed "Into The Pitt"
Completed "Unsafe Working Conditions"
Completed "Free Labor"
Found All 100 Steel Ingots
Completed "Death From Above"
Completed "Shock Value"
Completed "Who Dares Wins"
Reached Level 30 with Bad Karma
Reached Level 30 with Neutral Karma
Reached Level 30 with Good Karma
Completed "The Local Flavor"
Completed "Walking With Spirits"
Completed "A Meeting of the Minds"
Discovered all locations within Point Lookout
Completed "Not of This World"
Completed "Among the Stars"
Completed "This Galaxy Ain't Big Enough…"
Collected all Alien Captive Recordings