Here is the full list of all 46 Adventure Time: Explore the Dungeon Because I DON'T KNOW! achievements.
Survive 25 Floors in one Nightosphere run.
Survive 15 Floors in one Nightosphere run.
Enter the Nightosphere.
Uncover Bubblegum's dark secret.
Collect every Sub-Weapon.
Complete all of Susan Strong's Quests.
Complete all of Mr. Pig's Quests.
Overcome the Guardians' punishment.
Fully upgrade Ice King.
Free Flame Princess.
Fully upgrade Marceline.
Free the Earl of Lemongrab.
Grab 50 Treasures on a single Treasure Floor.
Locate every Familiar.
Complete all of Tree Trunks' Quests.
Survive a Monster Floor
Weather Goliad and Stormo's psychic assault.
Upgrade a Sub-Weapon into a stronger one.
Rescue the Hyoomans.
Upgrade a character's Imagination.
Assist Gunter with a feisty feline.
Eat every Food item at least once.
Put Ice King in his place.
Upgrade a character's Focus.
Receive a Curse.
Outrun the stampeding prisoners.
Pick up every Item pickup at least once.
Upgrade a character's Rowdiness.
Buy something from the shop.
Outsmart the Demon Cat.
Complete a Quest for the Princess.
Upgrade a character's Thumps.
Return from the Dungeon alive.
Use a Special Attack.
Perform a Perfect Block.
Fully upgrade Finn.
Fully upgrade Jake.
Fully upgrade Cinnamon Bun.
Fully upgrade LSP.
Fully upgrade Lemongrab.
Fully upgrade Flame Princess.
Complete all of Princess Bubblegum's Quests.
Complete all of Starchy's Quests.
Survive 50 Floors in one Nightosphere run.
Collect every Token.
Find all of BMO's Game Cartridges.