Here is the full list of all 24 Tower in the Sky : Tactics Edition achievements.
Complete the tutorial mission.
Add a third member to your party.
Have a party with four members.
Win an item from a Tavern.
Rescue Claw or Godfreid.
Complete a Tavern level.
Defeat a challenge level.
Defeat the tree abomination.
Rescue Murdok or Arwyn.
Travel to another dimension in the pyramid, and survive.
Defeat Gnaw
Open the Gatehouse
Rescue Cookie or Leon
Complete the crystal fragments.
Defeat Malaco.
Rescue Frank or Djinn.
Fly to the tower.
Deactivate the tower.
Collect 34 weapons.
Collect 26 T-Shirts.
Collect 44 items.
Defeat 5 challenge levels.
Defeat 150 battles.
Slay 5000 enemies.