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