Here is the full list of all 20 Chasm achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Complete the game as a Mortal.
Complete the game on Hard difficulty.
Explore 100% of the map.
Defeat Ulak.
Unlock all the Bestiary entries.
Complete all villager sidequests.
Spend 5,000 gold.
Break all the crates in the game.
Find all the Journal Entries in the game.
Defeat the Shaman.
Find all the Powerups in the game.
Rescue all the missing villagers.
Become the Arena champion.
Defeat King Trell.
Defeat 1,000 enemies.
Defeat the Titan.
Defeat the Bone Worm.
Defeat a boss without getting hit.
Defeat the Wendigo.
Defeat 100 enemies.