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.
Defeat Ulak.
Unlock all the Bestiary entries.
Explore 100% of the map.
Break all the crates in the game.
Find all the Journal Entries in the game.
Defeat the Shaman.
Rescue all the missing villagers.
Find all the Powerups in the game.
Become the Arena champion.
Defeat King Trell.
Spend 5,000 gold.
Defeat the Titan.
Defeat 1,000 enemies.
Defeat the Bone Worm.
Defeat the Wendigo.
Defeat 100 enemies.