Even decades after they were released, people are still discovering new secrets about classic video games. Back in April, a Redditor found a 30-year-old Mike Tyson's Punch-Out!! Easter egg. And now there's new news about 1991's Tecmo Super Bowl.

A staple game of the original NES, Tecmo Super Bowl was the first football video game that featured both real NFL teams and players—and was made even more authentic with its injuries, fumbles, and bad weather conditions. Now, 25 years after the game’s release, one fan has discovered that it was supposed to have penalties, too.

NES modder Dave Brude just discovered a hidden referee animation for a false start penalty hidden in the game’s code, which he suspects would have been activated randomly during gameplay. Brude is a Tecmo Super Bowl enthusiast who has spent years modifying and updating the game with current NFL teams and rosters and new rules, such as the two-point conversion after a team scores a touchdown, which wasn’t introduced in the NFL until 1994.

If you have the original NES game and a Game Genie or other emulator, you can see the animation by using the codes “YLXEPAAE” and “NXVLTAKU.” It will replace the first down referee animation with the false start signal, though it won’t prompt an actual penalty—as that’s one real-life aspect of Tecmo Super Bowl that never made it to the official game.

[h/t Polygon]

Images courtesy TecmoBowlers/YouTube.