The Nintendo Switch Online has finally launched and with it the ability to enjoy a selection of NES games with additional features and online multiplayer. Nintendo plans to release more games in the future, and it seems like there will be the possibility to add more games to the list of available titles through unofficial means.

　　Retro Engine and Splatoon 2 modder kapu recently revealed that it might be possible in the future to add custom NES games complete with online multiplayer. The Switch NES games are plain .nes files and the GUI seems to be like the NES and SNES Classic one.

　　good lord #NintendoSwitchOnline's NES games are plain .nes files

　　GUI appears to be entirely LUA much like the S/NES Classic so people are gonna be able to go to town on this

　　The "database" file that contains a listing of all valid games is plaintext,- pic.twitter.com/bO8M4B7U5e

　　— kapu | the Gay. (@KapuccinoHeck) September 19, 2018

　　in theory you can easily add entirely new games and if both players were using the same file setup, could play online with them together.

　　Here's to hoping they didn't implement anticheat into it for whatever reason so us modders can enjoy official online games lol pic.twitter.com/L4e0BeSEsd

　　— kapu | the Gay. (@KapuccinoHeck) September 19, 2018

　　also of note is that there don't appear to be patch files like what the 3DS and WiiU Virtual Console commonly had so you wouldn't need to do any sort of fancy modification to get them working online, this is in theory of course because CFW is broken on 6.0 meaning I can't test

　　— kapu | the Gay. (@KapuccinoHeck) September 19, 2018

　　ok so

　　this is incredibly basic but it shows that fully custom games ARE possible!

　　hakchi for NES Nintendo Switch Online when?#NintendoSwitch #NintendoSwitchOnline #NES pic.twitter.com/OBYn3dLOtV

　　— kapu | the Gay. (@KapuccinoHeck) September 19, 2018

　　Just to clarify, currently I have no idea how to properly modify the game cover art to make it fully legitimate.

　　This is the only obstacle to making them look entirely correct from what I can tell.

　　Hopefully some more interest sparks and people start to dig into it!

　　— kapu | the Gay. (@KapuccinoHeck) September 19, 2018

　　At this point, after looking over things and talking with some people, I can safely come to the conclusion that the Nintendo Switch NES app is simply a quick port of the NES Classic's emulator kachikachi to Switch.

　　Good grief.

　　— kapu | the Gay. (@KapuccinoHeck) September 19, 2018

　　The list of available NES games on Nintendo Switch features some of the best games ever released for the system, such as Super Mario Bros., Super Mario Bros. 3 and others. More games will be released each month.

　　Nintendo Entertainment System – Nintendo Switch Online: Subscribers will have access to NES – Nintendo Switch Online, a compilation of classic NES games. The collection will initially include 20 games, with more added on a regular basis. At launch, previously announced games Balloon Fight, Dr. Mario and Super Mario Bros. 3 will be joined by Donkey Kong, Ice Climber, The Legend of Zelda, Mario Bros., Soccer, Super Mario Bros. and Tennis.

　　SoccerTennisDonkey Kong™Mario Bros.™Super Mario Bros.™Balloon Fight™Ice Climber™Dr. Mario™The Legend of Zelda™Super Mario Bros.™ 3Double DragonRiver City RansomGhosts'n Goblins™Tecmo BowlGradiusPro WrestlingExcitebike™Yoshi™Ice HockeyBaseball