Impoppable Difficulty is a difficulty in Bloons Adventure Time TD. There are 75 Rounds in this mode, and completing this mode rewards a Diamond Medal and a Diamond Chest. Unlike the other three difficulties, the Impoppable Difficulty is locked initially and must be unlocked by completing Extreme Difficulty on the respective track. It is the hardest type of difficulty in the game.

Similar to the mode with the same name in other BTD games, the player starts with only 1 life, although Powers like Apple Pie (as in Version 1.7) still adds extra lives. Also similar to the BTD6 Impoppable Difficulty, the highest ranked Bloon for this mode is BAD, which appears on the final round, and the second highest ranked Bloon, the DDT, first appears on Round 69, requiring the player to be well prepared for them. Impoppable Difficulty also has many difficulty modifiers for each track.

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