One of my favorite parts of Animal Crossing on the Gamecube was the ability to collect classic Nintendo games that could be set up in the form of Nintendo Entertainment System consoles within your virtual house. There were a variety of options, like Balloon Fight or Donkey Kong. And, apparently, Nintendo was considering adding a bit more functionality to the game’s emulator beyond just the titles included on the disc.
A security researcher by the name of James Chambers discovered the ability to load games into the emulator within the Animal Crossing’s twentyish year old code. Chambers realized that using the in-game NES item caused the game to search for ROM files contained on the player’s memory card. Using an emulator to test his theory, he was able to load Mega Man and a couple other games into Animal Crossing.
It is unclear what Nintendo was planning with this feature. They have, certainly, been known to do some oddball yet innovative things in the past. Perhaps this could have been a weird predecessor to the virtual console, because Animal Crossing was one of the easiest ways to play classic titles at that point in time.
Source: Ars Technica