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