Here is the full list of all 25 Chants of Sennaar achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Reaching the real end of the game
Finish the game (or not?)
Leave the Armory with the wrong disguise once the Call is made
Ring the Abbey bell three times
Attend the Bards' show in the Fortress
Rebuild all links in the game
See the captured monster in the Laboratories
See the Great Door of the Abbey open
Visit the revived Abbey Garden
Meet a Serf in the Abbey
Rebuild half of the links
Validate all glyphs in the game
Activate all Terminals
Reach Exile
Meet Bards in the Library
Take a trip in the Alchemists' cable car
Reach the Galleries
Rebuild a first link
Winning at both games in the Gardens
Validate half of the game's glyphs
Reach the Garden
Reach the Frontier
Discover the Preacher's corpse
Reach the Abbey
Fill in the Journal's first page