Here is the full list of all 54 Divinity: Original Sin - there are Enhanced Edition achievements worth 1,000 gamerscore.
You made it into Hunter's Edge.
You have saved the Homestead on the Shelter Plane at the End of Time.
You made Archibald king of the trolls.
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.
You helped Bairdotr deal with Jareth.
Brandon told you the truth about the mining guild.
You safely returned to the surface after the collapse of the mines.
You have found the White Witch!
You have released the elements from Boreas' staff.
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 defeated Evelyn and found Councillor Jake.
You have solved the Mirror Dungeon puzzle.
You found a job for the unemployed. They will work for Captain Jack.
You defeated the four elemental demons.
Sam and Maxine are going to be wed!
Zombie Nick will now do your bidding.
You killed the ghost of Pontius Pirate.
The Fabulous Five have left town.
Pulled the wrong lever in the Pontius Pirate's lever puzzle in the Black Cove.
You've found a silky souvenir.
Esmeralda is your primary suspect.
You passed the test! Well, one of many.
You've found the legendary teleportation devices of Rivellon
You met a talking shell called Ishmashell.
Try to sneak past Junius and Bibius…
Find an unconventional job for the unemployed.
Free Esmeralda from prison.
Brew a fine whisky for Hershel.
Decide Arhu is better off human.
Kill Cassandra to get hold of the soul forge repair ritual.
Safely enter Phantom Forest.
Find Zandalor.
Help Jahan face his demons.
Solve Bellegar's maze.
Enter the Source Temple.
Finish the Trial of Ascension.
Meet the legendary weresheep!
Totally, completely, and utterly finish the game.
Keep the Tenebrium for yourself.
Finish the game in Honour Mode.
Finish the game in Tactician Mode.
Forge the sisters' souls.
Enter the Gnik Barc Nni.
Learn all the skills within one skill tree.
Finish the game with the Lone Wolf trait.
Make Arhu a cat forever
Give Wolgraff his voice back.
Teach Madora the value of mercy.