You can find a “secret” level select menu in Sonic 3D Blast by shaking or hitting the game cartridge itself while it’s playing. But ... why? That’s a strange way to hide a bonus screen, and the trick seems to be reproducible.

The story behind this strange feature is explained by the person who created it in the video above. Games have to pass each platform’s certification process before release to test for bugs and to make sure everything meets the console’s specifications. It can be a grueling process, and failing certification can mean lost time or even missed release dates.

Traveller's Tales founder Jon Burt would hide error messages by turning what would have been a crash or glitch into a secret bonus screen or effect. This meant that bugs would feel like just another part of the game, and the title would pass certification.

The screen added to Sonic 3D Blast allowed you to skip to different stages, and the easiest way for players to create a glitch that would bring up the screen is to cause the cartridge to briefly lose contact with the Genesis itself by shaking or hitting it.

And now we all know the story behind this weird secret menu, and the world is better for it.