Are you familiar with oracles and their use? They are GM emulators and the way they work is not by adapting the rules so much as adding procedures to help in GMing yourself. (Most solo play is a matter of wearing multiple hats for player and GM.) Let me throw out a few links and you can check those out and see if the idea clicks for you.
CRGE - https://www.drivethrurpg.com/en/product/145426/crge-conjectural-roleplaying-gm-e... (pwyw)
FHiC - https://www.drivethrurpg.com/en/product/392514/four-houses-in-chaos (free)