Rikh’s campaign world is called Skyf. It is an Alderson disk, a type of megastructure built around a star. The star sits in the center of the disk and bounces up and down to create a day and night cycle. The powerful Majisters created Skyf as a home for thousands of races that are having their homeworlds destroyed by an expanding black hole. The Majisters oversee the world giving divine gifts to the pure while the impure develop sorcerous powers.
You can read more about Skyf here: https://rikhhart.com/skyf
Rikh is also a DM on the Dungeons and Dragons Podcast UK which you can check out here: https://thedungeonsanddragonspodcastteamuk.wordpress.com/listen-now/
His campaign should be starting soon after this episode is released, so stay tuned!
Skyf is too large to have a functional map of the whole space. Instead, here is a map of the region where one of Rikh’s campaigns takes place: Map of Kuchoma Taka Region