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.
Unlock all the Bestiary entries.
Explore 100% of the map.
Complete all villager sidequests.
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.
Defeat King Trell.
Become the Arena champion.
Spend 5,000 gold.
Defeat the Titan.
Defeat 1,000 enemies.
Defeat a boss without getting hit.
Defeat the Bone Worm.
Defeat the Wendigo.
Defeat 100 enemies.