1984 classic NES Golf is hidden within every Nintendo Switch, fans have found.
Not only that, but the retro sports game appears to have been updated with motion controls - which use the Switch's Joy-Con controllers.
NES Golf is baked into the system's firmware, Switchbrew discovered, alongside a preinstalled NES emulator. The files are named "flog" - which is golf backwards.
Fans have got the game working by unofficial means - but as yet there's no way to officially boot up the game and start playing.
Its inclusion is likely a test for Nintendo's own NES emulator. NES games such as Super Mario Bros., Pinball, and Punch-Out!! are on the way to Switch next year, as part of the system's upcoming paid online service.
Nintendo has already said these games will be updated with added multiplayer - so the addition of motion controls to Golf does not come as a huge surprise.
Indeed, motion controls made Wii Sports' Golf perhaps the best game in the Wii's pack-in collection. Also, Nintendo trivia fans, Wii Sports' Golf's courses are based off of those which appeared in NES Golf.
Nintendo is not due to start charging for its online service until next year, but originally planned to launch the feature this autumn. The appearance of NES Golf in the Switch's files now perhaps reflects that earlier plan.
Switch's `flog` NES emulator has a single empty file in its RomFS, called "AtLeastOneFile"... lol— Michael (@SciresM) July 7, 2017
Maybe NES Golf will be unlocked for everyone for free when the service goes live? In the meantime, the hunt is on for a backdoor or hidden button prompt to access NES Golf sooner rather than later.