An ultra-rare, fully playable but silent early prototype of Mike Tyson's Punch-Out!! has been dumped online, revealing major departures from the final 1987 NES release, including arcade-era character names, unused fighters, and only four accessible opponents. The Video Game History Foundation analyzed the unusual cartridge, reportedly found at a former Nintendo of America employee's garage sale and later sold for $45,000, highlighting its retail-style mask ROM chips and previously unseen roster entries like Rockyhead and Mongol Khan.