No missable achievements (plus 46 unknown)
Sign in with Steam or Xbox to track your progress, and:
Use a Special Attack.
Complete a Quest for the Princess.
Perform a Perfect Block.
Return from the Dungeon alive.
Upgrade a character's Thumps.
Buy something from the shop.
Upgrade a character's Rowdiness.
Pick up every Item pickup at least once.
Upgrade a character's Focus.
Upgrade a character's Imagination.
Survive a Monster Floor
Eat every Food item at least once.
Upgrade a Sub-Weapon into a stronger one.
Grab 50 Treasures on a single Treasure Floor.
Fully upgrade Marceline.
Fully upgrade Finn.
Fully upgrade Jake.
Fully upgrade Cinnamon Bun.
Find all of BMO's Game Cartridges.