> Using the console's background connectivity, a Nintendo 3DS in Sleep Mode can automatically discover other Nintendo 3DS systems within range, establish a connection, and exchange content for mutually played games, all transparently and without requiring any user input.
> For example, in Rhythm Heaven Megamix, if the user passes by someone with the same software, they will take on a figure-fighting duel challenge.
There's also a handful of free games that come with the console, so you're not limited to people who own the same games.
There was a puzzle one where you got a random starting piece, and you could copy one piece from each person you passed that they owned. Sometimes you'd go past someone with the entire puzzle, sometimes you'd already have all the pieces someone else did (which is kind of fun in its own right).
I miss that there's nothing like that on Switch, but it was not great for the battery life.
(actually, on the original DS there was a game called The World Ends With You that implemented this feature at the game level, too. OS-level is a big improvement, but it was still neat there, especially since it gave you a bonus even for passing DSes that didn't hvae the game running)
> Using the console's background connectivity, a Nintendo 3DS in Sleep Mode can automatically discover other Nintendo 3DS systems within range, establish a connection, and exchange content for mutually played games, all transparently and without requiring any user input.
> For example, in Rhythm Heaven Megamix, if the user passes by someone with the same software, they will take on a figure-fighting duel challenge.