It’s hard to say for sure — I cannot replicate this myself — but modders say they have found an emulator within the Nintendo Switch and a copy of all-time NES great Golf installed on it.
This is less about the game and more about the larger meaning. An emulator on every Switch would be a rather big deal. Moreover, as SwitchBrew.org noticed, this game packs instructions specific for the Joy-Con controllers, at least according to the images they supplied.
We emailed Nintendo of America to ask what was going on and received a reply from a representative that they were looking into it. It’s the weekend after all.
Switchbrew found Golf, un-cleverly disguised by the file name “flog” they say. That washed out of a dump of title names from the Nintendo Switch’s file system back in July. According to Github poster yellows8 the game is on every copy of the Switch OS going back to system 1.0. However, “It’s unknown what exactly triggers launching this title.” That’s assuming it can be launched.
Update: A Nintendo representative responded with “We have nothing to announce on this topic.”