a 2002 super mario bros. romhack by u1 (author of air and mario gear solid: mushroom eater), old pond, diving frog, and water sound is themed after the basho poem (one possible english translation of) which appears on its title screen. mario has been painted green to fill the titular role; enemy sprites have been changed to look like fish. background tiles have been entirely redrawn to provide a more diverse underwater environment for the aquatic-themed hack.

in the final stage of nintendo’s super mario bros., r&d4 places a firebar in an underwater area. u1’s hack continues this work, reinventing each element of super mario bros. as part of mario’s underwater world. in this watery domain which strips our hero of his most essential ability - jumping - patterns of enemy movement become that much more crucial: they must be seen and appreciated for what they are, as frog mario’s only option is to creep through the spaces between them as a touhou player might sneak through the cracks between bullets. each stage is crafted around a singular theme - one begins with a clever inversion of a trope of the original super mario: mario enters a pipe and is whisked upward from an underwater to aboveground stage. as a sea creature, this mario is more vulnerable out of water than in, and platforming in the aboveground areas becomes almost a kind of puzzle.