I create solo TTRPGs, so along with a setting I'd need rules/mechanics for play.

Does that fit with the theme of the jam? e.g. if the <8 pages was both a description of the world, and the rules for how to play? Or is that moving away from the intention?

We're very loose with the definition of setting material here, so as long as setting material is prominently featured within the 8 pages then the inclusion of mechanics is totally fine