I hate to be that guy, but I think there’s a good chance this game is going to disappoint a lot of people who loved the Wii Sports titles on the Wii and Wii U.
The Wii controllers contained gyroscopes and accelerometers, but also used the light bar to track their orientation in 3D space. The joycons only have gyroscopes and accelerometers, so they know how they’re orientated and when they’re in motion, but not where they are relative to anything else. This means they’re physically incapable of reproducing the 1:1 movement tracking that made the Wii games so intuitive and enjoyable.
If you watch the short volleyball demo in the Nintendo Direct or any of the other trailers the lack of tracking is really apparent. It recognises the movements, (e.g. bring both hands overhead to spike the ball etc.) but it’s clearly not 1:1. Effectively, it’s just a gesture based control scheme.
I’ve seen a lot of people questioning why some of the sports from past titles have been omitted. I suspect this is why. They wouldn’t work.
I’d love to be wrong, but I think this is going to be a letdown for people expecting something akin to the Wii games. It’s going to feel like a big step backwards from a game released 18 years ago.