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