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.
Explore 100% of the map.
Unlock all the Bestiary entries.
Complete all villager sidequests.
Rescue all the missing villagers.
Find all the Journal Entries in the game.
Find all the Powerups in the game.
Become the Arena champion.
Complete the game on Hard difficulty.
Defeat Ulak.
Spend 5,000 gold.
Break all the crates in the game.
Defeat the Shaman.
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.