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