I had never come across this before and only recently inherited an used Nintendo Wii, but it looks like the Wii still has some tricks left. Released in 2006 and discontinued in 2013, the Wii hardware supports other uses like running emulators of other gaming consoles. By modding the Wii with the Homebrew Channel, users can install emulators for the NES, Genesis, and other old school favorites.
Overall, the steps look straightforward and well documented. As a follow-up project, you can also connect an external USB drive to hold and launch games from. To be on the safe side, it seems a wired controller is recommended, not only for navigating the menus, but then when you have your retro games going, the control and button layout of the wired controller makes more sense for games from yesteryear.