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