I only know of one on the marketplace, but I know there are solo print systems and adventures. Haven't played any myself though. Plot Armor on the marketplace: <a href="https://marketplace.roll20.net/browse/module/10633/plot-armor" rel="nofollow">https://marketplace.roll20.net/browse/module/10633/plot-armor</a> Loan Wolf and Fabled Lands are a couple names I know I have read about being solo rpg systems/games on forum or reddit posts, but I don't know more than the names.