Here is the full list of all 37 Timespinner achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Find all Melee Orbs.
Defeat Ifrit in battle. (Normal or Nightmare mode only)
Collect all Letters.
Collect all Memories, Letters, and Downloads.
End the War of Sisters before any blood is shed.
Defeat Nightmare in battle. (Normal or Nightmare mode only)
Defeat the Sandman in battle. (Normal or Nightmare mode only)
Defeat the Ravenlord in battle. (Normal or Nightmare mode only)
Defeat the ruler of Lachiem.
Defeat Emperor Nuvius in battle. (Normal or Nightmare mode only)
Collect all Memories.
Defeat Xarion in battle. (Normal or Nightmare mode only)
Finish all character quests.
Defeat Cantoran in battle. (Normal or Nightmare mode only)
Collect all Downloads.
Finish a character's entire quest line.
Defeat Genza in battle. (Normal or Nightmare mode only)
Defeat The Maw in battle. (Normal or Nightmare mode only)
Have an Alchemist make you a new Passive ring.
Defeat Aelana in battle. (Normal or Nightmare mode only)
Defeat the Golden Idol in battle. (Normal or Nightmare mode only)
Defeat the Azure Queen in battle. (Normal or Nightmare mode only)
Finish a character's quest.
Have an Alchemist make you a new Spell.
Defeat Varndagroth in battle. (Normal or Nightmare mode only)
Find a new Melee Orb.
Defeat the Feline Sentry in battle. (Normal or Nightmare mode only)
Find your first Familiar companion.
Achieve all possible feats on the same save file.
Prevent the Qaelans from being persecuted by the Empire.
Beat the game on Nightmare mode.
Acquire every Orb Spell.
Collect all Familiar companions.
Discover 100% of the map.
Obtain an Orb without breaking its pedestal.
Defeat a boss without stopping time nor taking damage.
Acquire every Orb Passive.