Here is the full list of all 54 Divinity: Original Sin - there are Enhanced Edition achievements worth 1,000 gamerscore.
You tried to sneak past Junius and Bibius... And failed!
You freed Esmeralda from prison.
You kept the Tenebrium for yourself.
You found a job for the unemployed with the Fabulous Five!
You locked up Arhu and forced him to become human.
Arhu is a cat forever! If you ever have a problem with mice, you know who to call.
You've taught Madora the value of mercy.
You've found a silky souvenir.
You made Archibald king of the trolls.
You have totally, completely, and utterly finished the game.
You finished the game with the Lone Wolf trait.
You forged Icara and Leandra's souls.
You have entered the Gnik Barc Nni.
You helped Bairdotr deal with Jareth.
You have learned all the skills within one skill tree.
You've given Wolgraff his voice back.
You have met the legendary weresheep!
You have found Zandalor.
You have finished the Trial of Ascension.
You have made it into the Source Temple.
You helped Jahan face his demons.
You have killed Cassandra to get hold of the soul forge repair ritual.
You have solved Bellegar's maze.
You have safely entered Phantom Forest.
You brewed a fine whisky for Hershel.
You made it into Hunter's Edge.
You have saved the Homestead on the Shelter Plane at the End of Time.
You have created a spell that makes Death Knights vulnerable.
You talked to Icara and learned more about Leandra's plans.
You came face-to-face with Mangoth himself.
Sam and Maxine are going to be wed!
You have found the White Witch!
You have released the elements from Boreas' staff.
You safely returned to the surface after the collapse of the mines.
Brandon told you the truth about the mining guild.
You have met Leandra in Hiberheim.
You found a way to open the barrier without harming any mushrooms.
You saved Bonnie!
You delivered Blossius' will to Marisa totally unaltered.
You informed Selenia about the source of the undead.
You killed the ghost of Pontius Pirate.
Pulled the wrong lever in the Pontius Pirate's lever puzzle in the Black Cove.
Zombie Nick will now do your bidding.
The Fabulous Five have left town.
You defeated Evelyn and found Councillor Jake.
You defeated the four elemental demons.
You have solved the Mirror Dungeon puzzle.
You passed the test! Well, one of many.
You found a job for the unemployed. They will work for Captain Jack.
Esmeralda is your primary suspect.
You've found the legendary teleportation devices of Rivellon
You met a talking shell called Ishmashell.
Finish the game in Honour Mode.
Finish the game in Tactician Mode.