Yeah, I am helping my daughter run her first campaign. She wants it based on some story/universe she is into called the Backrooms.
I’m thinking that the players start out as blank slates, generic characters with access to only the Basic Moves from Dungeon World. Maybe everyone starts with the same HP, but gets to choose their attributes, or something like that. Then, as the GM, you set up opportunities for the characters to meet the conditions of the various Compendium classes, and then they can take moves from those Compendium Classes when they level-up. The “themes” method of dungeon building from the PW handbook could be very useful, here.
Example stolen from the internet: the Dragon Slayer Compendium Class: When you drink the still-warm heartblood of a dragon, the next time you level up, you may choose this move… Usually the first move of the class is the best, and taking it opens up the option to take further moves at next level-up. I think it might be cool if the characters end up as composite classes, with moves collected from various classes.