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
Rebuild all links in the game
Meet a Serf in the Abbey
Visit the revived Abbey Garden
Finish the game (or not?)
Validate all glyphs in the game
See the captured monster in the Laboratories
Rebuild half of the links
Activate all Terminals
Reach Exile
Take a trip in the Alchemists' cable car
Meet Bards in the Library
Attend the Bards' show in the Fortress
Reach the Galleries
Leave the Armory with the wrong disguise once the Call is made
See the Great Door of the Abbey open
Ring the Abbey bell three times
Validate half of the game's glyphs
Rebuild a first link
Reach the Garden
Winning at both games in the Gardens
Reach the Frontier
Discover the Preacher's corpse
Reach the Abbey
Fill in the Journal's first page