Full list of all 76 Dragon Age: Origins achievements worth 1,750 gamerscore. It takes around 60-80 hours to unlock all of the achievements in the base game.
The base game contains 50 achievements worth 1,000 Gamerscore, and there are 8 DLC packs containing 26 achievements worth 750 Gamerscore.
Completed the Dwarf Commoner origin story
Completed the Dalish Elf origin story
Completed the Magi origin story
Completed Ostagar
Used the Grey Warden treaties to recruit all possible allies
Completed "The Arl of Redcliffe"
Completed "The Landsmeet"
The ultimate sacrifice was made in defense of Ferelden
Sided with the mages in "Broken Circle"
Sided with the templars in "Broken Circle"
Sided with the elves in "Nature of the Beast"
Defied the Cult of Andraste in "The Urn of Sacred Ashes"
Sided with Harrowmont in "A Paragon of Her Kind"
Preserved the Anvil of the Void
Completed an origin story without the main character ever falling in battle
Main character achieved level 20 as a warrior
Defeated the dragon guarding the Urn of Sacred Ashes
Completed a Chanter's Board quest
Killed 100 darkspawn
Killed 500 darkspawn
Preserved the lives of half the troops at Denerim's Gates in "The Final Battle"
Crafted an item
Succeeded at five difficult Persuasion attempts
Experienced the thrill of romance with Morrigan
Main character learned a specialization
Sided with the Cult of Andraste in "The Urn Of Sacred Ashes"
Sided with the werewolves in "Nature of the Beast"
Main character inflicted 250 damage with a single hit
Main character achieved level 20 as a rogue
Completed the City Elf origin story
Main character learned two specializations
Used a tome to improve the main character's attributes, talents, spells, or skills
Completed the Dwarf Noble origin story
Completed the Human Noble origin story
Complete 15 job-board quests
Across all playthroughs, recruited all party members
Across all playthroughs, experienced all possible romances
Across all playthroughs, discovered all possible endings
Defeated the Archdemon and, through a dark ritual with Morrigan, spared your own life
Sided with Bhelen in "A Paragon of Her Kind"
Destroyed the Anvil of the Void
Set foot in every area in the game
Main character achieved level 20 as a mage
Killed 1000 darkspawn
Succeeded at 25 difficult Persuasion attempts
Succeeded at five difficult Intimidate attempts
Succeeded at 10 difficult Intimidate attempts
Experienced the thrill of romance with Alistair
Experienced the thrill of romance with Zevran
Experienced the thrill of romance with Leliana
Completed "The Golem in Honnleath" (The Stone Prisoner DLC)
Completed "A Golem's Memories" (The Stone Prisoner DLC)
Defeated the ogre that killed King Cailan
Destroyed the broodmothers in Kal'Hirol
Escaped the silverite mines
Defeated the baroness
Saved the city of Amaranthine
Completed Dragon Age: Origins - Awakening
Reached level 30
Acquired all upgrades for Vigil's Keep
Saved Vigil's Keep
Handed victory to the archdemon by killing Ferelden's last Grey Warden. (Darkspawn Chronicles)
Earned maximum approval from all thrall types. (Darkspawn Chronicles)
Keep the initial ogre alive as your thrall throughout the entire module. (Darkspawn Chronicles)
Heard Leliana's version of her betrayal.
Collected and assembled the Battledress of the Provocateur.
Destroyed the career of Guard Captain Eams.
Defeated the Harvester
Defeated the Harvester on Hard or Nightmare difficulty
Gathered all of the research notes in Amgarrak
Completed "Witch Hunt"
Completed the scrying ritual
Defeated the varterral on Hard or Nightmare difficulty
Gathered the lost lore of Cadash Thaig
Completed "Soldier's Peak" (Warden’s Keep DLC)
Took advantage of Avernus's research (Warden’s Keep DLC)