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