In a move possibly designed to allow more than 17 people in the world to finish Zelda II: The Adventure of Link, Nintendo is adding a rewind feature to NES games on the Switch. As you can see from the video above, you can hold down ZL and ZR to access a row of snapshots in time that you can resume from. The feature is coming on July 17th.

NES games are part of the Nintendo Switch Online service; members have access to a collection that currently stands at 44 titles, including most of the system’s biggest first-party hits. The latest releases, Donkey Kong 3 and Wrecking Crew, will also be added to the service on July 17th.

https://www.theverge.com/2019/7/9/20688409/nintendo-switch-nes-games-july-rewind