RP6

Really, most TTRPG rules boil down to "I can do this if the GM says I can." We have certain bits set down as rules, so it's an inviolable right that you can add your Strength modifier to Strength rolls when you're playing D&D, but there's equally enough GM fiat and jiggery-pokery behind the scenes that setting the Target Number higher can completely negate that modifier. The dice sit in the middle as a charming arbitrator, and to remove some of the perceived responsibility from the GM, but they're in charge and you're gambolling for their favour.

Anyway, to grossly oversimplify it: all roleplaying games are bullshit and are an exercise in framing fictional concerns modulated through the prism of social interaction between players and GM. So when I was writing the simplest possible one, I wanted to say the quiet part out loud and condense almost all the rules into "convince the GM that it's a good idea." RP6 is that.

It's pretty much the purest form of roleplaying you can have, and everything else we do as games designers is guide rails that push the story, tone, pacing etc. in different directions. (Not that "pure" implies "best," here. Unprocessed sugar cane is all well and good but I can't make a cake with it, can I?)