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