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