Mario NES 1.5 is a game that never was, but its absence is more instructive than its presence. It highlights the radical, almost reckless creativity of late-1980s Nintendo, where sequels were either sadistically difficult (Japan) or borrowed from unrelated arcade games (USA). The non-existence of a clean 1.5 iteration forced developers and players alike to adapt to sudden paradigm shifts, a trend that would continue with Super Mario 64 .
Beyond the fan projects, the original NES game contains several hidden or "interesting" text and data elements: MarioNES 1.5
: You can edit the 20 areas across the 7 worlds found in the original game structure. Three-Window Interface Mario NES 1
For users and developers working with MarioNES 1.5, the following technical specifications are generally relevant: Engine Integration Beyond the fan projects, the original NES game