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.
Unlock all the Bestiary entries.
Defeat a boss without getting hit.
Complete all villager sidequests.
Defeat Ulak.
Explore 100% of the map.
Break all the crates in the game.
Find all the Journal Entries in the game.
Spend 5,000 gold.
Defeat the Shaman.
Find all the Powerups in the game.
Rescue all the missing villagers.
Defeat King Trell.
Become the Arena champion.
Defeat 1,000 enemies.
Defeat the Titan.
Defeat the Bone Worm.
Defeat the Wendigo.
Defeat 100 enemies.