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