Super Mariofell 64 is a single level rom hack which contains an alternative universe version of The Princess's Secret Slide based on the Undertale AU "Underfell" but applied to Super Mario 64, which inverts the morals of the characters. The rom hack was released by SiIvaGunner during their April Fools' 2026 event, disguised as a playlist link under the video "The Princess's Sinistar Slide - Super Mariofell 64".