https://www.gamespot.com/articles/nintendo-switch-online-adds-three-more-nes-games-n/1100-6462253/

One of the benefits you receive for subscribing to the Nintendo Switch Online service is access to a library of classic NES games, all of which support online play. 20 titles are currently available on the service, with Nintendo promising to add more to the library regularly. It turns out we won't have to wait too long for the first new batch of titles to arrive.

Nintendo confirmed on Twitter that three more vintage games are coming to Nintendo Switch Online's NES library next week, on October 10: Solomon's Key, Super Dodge Ball, and NES Open Tournament Golf. All three titles will be available in each region.