It sounds like you’re referring to a ROM hack or mod of Super Mario Bros. Special (the 1988 PC-88 port by Hudson Soft). That version is already notorious for its strange physics, flickery graphics, and altered level design compared to the NES original.
When he reached the final axe, the screen didn't fade to black. Instead, a text box appeared in a font the PC-88 shouldn't have been able to render. "Is this better, Kaito?" Super Mario Bros Special Pc 88 Rom BETTER
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