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