Fans of the early-2000s era GameCube version of the original Animal Crossing likely remember the game including a handful of emulated NES titles that could be played by obtaining in-game items for your house. What players back then didn't know is that the NES emulator in Animal Crossing can also be used to play any generic NES ROM stored on a GameCube memory card.
Security researcher James Chambers discovered the previously unused and undocumented feature buried in the original Animal Crossing game code and detailed his methodology and findings in a technically oriented Medium post this week.
The key to opening Animal Crossing's NES emulator is the game's generic "NES console" item. Usually, this item simply tells players who try to use it that "I want to play my NES, but I don't have any software" (separate in-game items are used to play the NES ROMs that are included on the Animal Crossing disc).