Here is the full list of all 20 Chasm achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Defeat Ulak.
Unlock all the Bestiary entries.
Complete all villager sidequests.
Find all the Journal Entries in the game.
Spend 5,000 gold.
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 the Bone Worm.
Defeat the Wendigo.
Defeat 100 enemies.
Break all the crates in the game.
Explore 100% of the map.
Defeat a boss without getting hit.
Complete the game on Hard difficulty.
Complete the game as a Mortal.