Nintendo has finally unveiled some details on the online service coming to the Switch. Nintendo Switch Online is the new name being given to the online service and it will officially be launching sometime in 2018, before then Nintendo Switch Online will be free for all Nintendo Switch owners.
Nintendo Switch Online also comes with its very own dedicated smartphone app "that connects to your Nintendo Switch system and helps you connect with friends for online play sessions." NSO will allow you to play online with or against friends and strangers and will be free until the full service launches, afterwards Nintendo says "most" games will require the paid service in order to play online. This seems to indicate it will be up to each developer and publisher as to whether their game will require NSO or not. Also coming during the free trial period will be a limited version of the companion app for NSO. The app will "let you invite friends to play online, set play appointments, and chat with friends during online matches in compatible games─all from your smart device." It looks like Nintendo is setting up the app to be the main way you will be interacting with the NSO service.
Another part of NSO will be the "Classic Game Selection" (name subject to change) that will provide subscribers with access to a compilation of classic games with added online play like Super Mario Bros. 3, Dr. Mario, and Balloon Fight. Talking to Kotaku, Nintendo stated “Nintendo Switch Online subscribers will have ongoing access to a library of classic games with added online play. Users can play as many of the games as they want, as often as they like, as long as they have an active subscription.” Nintendo also said “More games will be announced at a later date. At launch the classic game library will include NES games. Super NES games continue to be under consideration, but we have nothing further to announce at this time.” and as far the Virtual Console goes Nintendo left Kotaku in a "nothing to announce on this topic." NSO will also give subscribers access to Nintendo eShop deals with "may include" discounts on games and content. NSO is currently being priced at $19.99 a year in USD with pricing for other countries being announced closer to launch.
Hori also revealed their new Splatoon 2 chat headset in a recent tweet, which also gives us a look at how the chat system for NSO will function. The pictures show that you'll need to connect an AUX cable from your phone, that is using the app, to an adapter that will also have another cable connecting to your Switch, then all of that connecting through the adapter to your headset. So it seems Hori has decided this is its solution to hearing voice chat and game audio at the same time while playing.