Here is the full list of all 13 Adventures of Shuggy achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Complete all the CoOp levels.
Complete all of the clocktower levels.
Defeat the guardian of the clocktower.
Complete all the Teleporting Troubles levels.
Complete "Extending Platform" without using the rope.
Complete all of the graveyard levels.
Complete "Spike Dodging" without using the teleporter.
Complete all of the boiler room levels.
Complete all of the gallery levels.
Complete all of the dungeon levels.
Complete "In One Way..." in less than 16 seconds.
Complete a level containing Shmu.
Complete a time travel level.