Overview
- An anonymous collector who won the cartridge at auction allowed The Cutting Room Floor to share a full ROM dump for public study.
- The early English build predates any Mike Tyson branding and lacks sound code, features only four fights—Glass Joe, Bald Bull, King Hippo, Don Flamenco—then loops after training, and its text still cites arcade‑era names like Piston Hurricane and Pizza Pasta.
- A hidden debug menu lets players control unfinished opponents and step through moves, which produces broken animations and other visual glitches.
- Video Game History Foundation’s Frank Cifaldi calls it an unusually early look at a famous first‑party Nintendo game, noting he has not seen a comparable NES prototype in decades of research.
- Coverage cites an alleged origin in a former Nintendo of America employee’s garage sale, and reports disagree on the auction total, with figures of $45,000 and more than $60,000 both reported.