Mario.exe appears as an easter egg in INKBOWSER.exe, with a 1/3 chance of being found in World 1-2. Mario.exe then appears in a Game Over screen staring at the player, blood on his overalls, with a decapitated Luigi and Toad around him. After a while, Mario.exe armed with a sword will fly at the player from the left of the screen, causing the screen to cut to black with blood splattered onto it. Mario.exe appears standing at the end of World E-0, disappearing into red mist when touched. Mario.exe's face jumpscares the player once they complete the level. Mario.exe punches the princess off the cliff and then quickly runs to the right, decapitating Luigi if the player fails to jump out of the way. He next appears in World 1-3 after the player turns back from the end of the level, standing at the edge of a cliff with Princess Peach. Mario.exe can be briefly seen in World 1-2 during the section where the player must survive several spiked blocks, watching them from the ledge they had previously dropped down from. He appears after the flagpole in World 1-1, burning down the castle to kill the Toads within and quickly running away. He first appears on the title screen, replacing Mario for a split second once the player selects Luigi.
Mario.exe appears as the antagonist of Mario.exe, seen in all four of the game's levels.
