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.
Defeat Ulak.
Unlock all the Bestiary entries.
Spend 5,000 gold.
Complete all villager sidequests.
Explore 100% of the map.
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 a boss without getting hit.
Defeat the Bone Worm.
Defeat the Wendigo.
Defeat 100 enemies.