Here is the full list of all 97 Divinity: Original Sin 2 achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Arrive at Arx
Enter The Arena of the One
Convince Alexandar to ally with you
Discover the hidden entrance to the Academy
Enter the Academy
Convince all party members to let you ascend
Sebille: Destroy the Mother Tree
Sebille: Serve the Mother Tree
Sebille: Kill the Master
Pray at every altar on the Nameless Isle
Arrive at the Nameless Isle
Destroy every Voidwoken egg in Reaper's Cove
Use the Curse skill
Learn of the Council of Seven's location from a higher power
Unlock your third Source Point slot
Awaken the corrupted Ancestor Tree on Bloodmoon Island
Learn of the Council of Seven's location from The Advocate
Unlock your second Source Point slot
Learn of the Council of Seven's location from Malady
Escort Saheila outside without fighting the Lone Wolves
Perform successful surgery on Natalie
Correctly answer all of Crispin's questions
Tame Featherfall
Kill Andras, the necromantic dog
Set Gareth on a path of vengeance
Set Gareth on a path of reconciliation
Take the ferry to Bloodmoon Island
Lockpick your way into Mordus' hidden lair
Become champion of the Driftwood Arena
Receive Dorotya's kiss
Serve Garvan the tainted stew
Speak to an animal's spirit
Adopt Peeper
Meet Meistr Siva
Help free Mari from the Voidwoken
Arrive at Reaper's Coast
Escape Dallis' siege on the Lady Vengeance without killing every minion
Enter the Hall of Echoes
Escape Dallis' siege on the Lady Vengeance after killing every minion
Take command of the Lady Vengeance
Welcome Tarquin to the Seekers' service
Defeat Alexandar in Fort Joy
Kill Slane
Kill Radeka
Craft a scroll
Craft a skill
Craft a grenade
Rescue Gareth from Braccus' Armoury
Use your first Source Skill
Arrive at the Sanctuary of Amadia
Equip runes to all of an item's available slots
Face a higher power
Shapeshift into every race
Escort the Black Cat out of Fort Joy
Kill an enemy using Teleportation
Flee Fort Joy for good
Remove your Source Collar
Become champion of the Fort Joy arena
Get caught breaking the law
Gain the Hero tag
Escape the kraken's clutches
Arrive at Reaper's Eye
Win a persuasion event
Perform a successful theft
Successfully begin a Game Master session
Successfully begin a match in Arena Mode
Force Dallis to retreat from combat in Fort Joy
Obtain Anathema
Swear to the Covenant
Gain entrance to Lucian's Crypt without following the Path of Blood
Successfully walk the Path of Blood
Defeated the Kraken
Ascend to Divinity
Share Source with all of Rivellon
Purge Rivellon of all Source
Submit to the God King
Share Divinity with The Doctor
The Red Prince: Kill the Red Princess
The Red Prince: Become the father of dragons
Lohse: Embrace your demon
Lohse: Banish your demon
Fane: Return the Eternals to Rivellon
Fane: Embrace this strange new world
Ifan: Kill Lucian
Ifan: Forgive Lucian
Beast: Assassinate the Queen
Persuade Toyseller Sanders to give you his amulet
Discover Reimond's Lair
Rescue Arhu
Defeat Adramahlihk
Make a deal with Adramahlihk
Beast: Ally with the Queen
Complete the game in Explorer Mode
Complete the game in Classic Mode
Complete the game in Tactician Mode
Gain the Villain tag
Complete the game in Honour Mode