The Gameboy was one of the first handheld videogame devices (Handy-boy was the first, no idea). It had hundreds of games, and while it provided a lot of entertainment for individuals it also allowed for people to play between each other. Since there was no internet at the time, people used a cable called “Link cable” to connect their devices together and play. Looking a bit into the subject I found the connector was called a DMG-04.