Message:I would think most systems can be played solo with the right generator. I've played DnD solo (group) without a Ref or more correctly a computer program hitting us repeatedly with random encounters. The rest is imagination to fill in the plot between.
My suggestion for solo start is Chronicles of the Outlands. Generate a character. Use the castle generator or manor generator on this site.
https://spacegamer.com/docourt.asp
Solve a problem at the place generated. Slay a Threat Number one monster. See how the mechanics run. On to the next manor for more. Add specific skill tests and problems as you go. If you wish to have a party of three, manageable, so be it. Otherwise, see what happens to you as the wandering Hero. You may die, but will your sword and horse to the next hero.
I am writing (maybe a year or two off) a solo Fantasy Catch-Up table that will work as a self-contained solo fantasy adventure generator.
Here's a link to Chronicles games I have run.
https://www.youtube.com/playlist?list=PLUHNrIqM1T1PNpKXcygjp7XBonlH-70Gq
Here is a demo of me running Baronial Lifestyles and that castle generator;
https://www.youtube.com/watch?v=l4kyw9ZMfY0&list=PLUHNrIqM1T1OWSmweHXTwIMGtrSfc2Khn&index=2
Any questions, post them here. And let me know what happens to your 'toon.
Yours,
IronRed
04-Mar-2021