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