On the tabletop roleplaying game actual-play show Dimension 20, the theme, game, and setting change between seasons. Though the show does have a main cast it returns to for specific seasons, known as the Intrepid Heroes, it also rotates through different players for other campaigns. Occasionally, Dimension 20 will also have a guest serve as the Dungeon Master or Game Master.
Source：https://www.cbr.com/dimension-20-every-guest-dm-and-what-they-ran/
