My ideal RPG: an 8-12 page booklet with a moderm infographic-style design that explains all the rules. All the reference stuff (monsters, magic, feats, classes, playbooks, you name it) as cards, bigger or smaller, depending on the need.
The goal would be to make it as accessible as possible, ideally to be picked up and learned in 15-30 minutes. Just like board games. Some publishers did try that in the late 80s, but it went nowhere.
If I get angry enough, I'll do it. 😀​