Here is the full list of all 36 The Island: Into The Mist achievements.
You reached to Soldier island.
Dambi finds something wrong with the warehouse.
Sehan unlocks the communication security.
Seul finds the headsman's hidden room.
Akane joins the party.
Hoon joins back alive.
Seul picks up the hammer.
Sehan tries to persuade Seona.
Sua claims to stay together.
Sua claims to go back to the communication center.
Sua claims to fix the ship.
Sua claims to trust Akane.
Sua claims to trust Gyu.
Jo destorys the lock with an iron lever.
Sehan waits for Dambi.
You saw the first bad ending.
You saw all the bad endings.
You saw the first happy ending.
You saw all the happy endings.
You saw 'Last of Us' ending.
You saw 'A Friend' ending.
You saw 'Just Two of Us' ending.
You saw 'Solitude' ending.
You saw 'Second Life' ending.
You saw 'Betrayer' ending.
You saw 'Happy End' ending.
You unlocked a main stream.
You unlocked all the main streams.
You unlocked Sehan and Dambi's mainstreams.
You unlocked Min and Sua's mainstream.
You unlocked Seul and Hoon's mainstream.
...
You unlocked Akane's mainstream.
You unlocked Jo's mainstream.
You found the Nexus.
You completed all achievements.