A Koopa's Revenge is a Mario fangame where you play as one mean Koopa. Angry at being another footstool of the Mario Bros., a Koopa decides to go on a rampage and kill as many denizens of the Mushroom Kingdom as possible, Along the way, he can kidnap baby versions of Mario, Luigi, Wario, and Waluigi as collectibles despite the fact that their adult versions are in the game and there doesn't appear to be any time travel involved.

sobble_p completes all 16 levels and kills every named character from the Mushroom Kingdom, glitching the game whenever there's downtime for extra entertainment.