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