Standing on a neon-lit platform in virtual space you’ll touch or punch (depending on how intense a workout you want) colored targets with the matching colored orbs in your hand while dodging oncoming obstacles.
The Moon Rider Search page says you can search from 15,000 songs, which they’ve categorized into 18 different genres for an easy way to search by the type of music you want. Moon Rider draws songs and maps from the same library of community-created content that Beat Saber does so it’s a good way to also see what kinds of songs/maps you could add to that game (if you can understand the complicated steps to do so). There are five levels of difficulty in total, from Easy to Supernova, although the levels available for any given song differ by song. A really nice feature is the playlists created by other users that solves the issue of having to select a new song after each one, disrupting your workout.
Moon Rider is free and is accessed through the Browser on your headset at moonrider.xyz.