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 8 with Bad 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
Completed "Take it Back!"
Kill all the Super Mutant Behemoths
Killed 300 people
Hacked 50 terminals
Completed "The Nuka-Cola Challenge"
Made one of every custom weapon
Completed "Rescue from Paradise"
Completed "The American Dream"
Collected 20 Vault-Tec Bobbleheads
Completed "Finding the Garden of Eden"
Completed "Picking up the Trail"
Completed "Trouble on the Homefront"
Completed "The Waters of Life"
Won 50 Speech Challenges
Completed "Agatha's Song"
Completed "Strictly Business"
Reached Level 20 with Good Karma
Completed "Big Trouble in Big Town"
Completed "Reilly's Rangers"
Discovered 100 locations
Completed "Oasis"
Completed "Head of State"
Picked 50 locks
Collected 10 Vault-Tec Bobbleheads
Completed "You Gotta Shoot 'Em in the Head"
Completed "Tranquility Lane"
Completed "Scientific Pursuits"
Killed 300 creatures
Reached Level 14 with Good Karma
Completed "The Superhuman Gambit"
Placed a grenade or mine while pickpocketing
Completed "Stealing Independence"
Completed "Galaxy News Radio"
Completed "Following in His Footsteps"
Completed "Tenpenny Tower"
Completed "The Wasteland Survival Guide"
Reached Level 8 with Good Karma
Completed "Those!"
Completed "The Replicated Man"
Completed "Blood Ties"
Completed "The Power of the Atom"
Completed "Escape!"
Took the G.O.A.T.
Got the Pip-Boy 3000
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 "Who Dares Wins"
Completed "Shock Value"
Reached Level 30 with Neutral Karma
Reached Level 30 with Bad Karma
Reached Level 30 with Good Karma
Completed "Death From Above"
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