More than two decades after the first Mortal Kombat game appeared in arcades everywhere, a player has discovered a secret menu of hidden options left behind by its creator.

Dubbed the “EJB Menu,” after Mortal Kombat creator Ed J. Boon, it’s unlockable by pressing buttons in the right combination on arcade cabinets of the first three Mortal Kombat games, as the video above from YourMKArcadeSource details. The menu includes lots of backdoor options, like being able to watch each character’s endings without actually beating the game, adding your initials to the leaderboard without actually scoring any points, and a whole Space Invaders-like minigame.

It’s not clear if there are more EJB menus in later Mortal Kombat games, but as far as the first three are concerned, this is a major easter egg hidden in games people have been playing a lot for about 24 years. And if this is in there, who knows what else might still be secreted away in the bowels of Mortal Kombat (or even other old arcade games for that matter)? If you’re thinking “probably nothing,” keep in mind that’s what lots of people thought until this very week.

Via Gizmodo.