https://www.cnet.com/news/nintendo-switch-3ds-new-details-2018-how-to-watch-live/

Nintendo has also teased details about its forthcoming Switch Online service, including the ability to play the original Mario Bros. game in co-op mode. 

The company says it will release 20 free NES games for subscribers of the service, which costs $3.99 a month, or $20 a year. The service is expected to go live in the second half of September.