rubs hands together Eeeeexellent! We’ve converted another.
There are so many ways to play solo. It’s hard to recommend something specific without knowing what kind of game you’re looking for.
Ironsworn is a full-on ruleset for playing a solo game. It didn’t work for me because it was world building as well as playing through a game. I found the world building really challenging. That said, you might find it’s a perfect fit if you like to homebrew as a GM. The great thing about it is that you get rollable tables to help give you ideas. This attempts to replicate others at the table throwing out ideas.
Some solo players look for books of rollable tables to play. They just use the system their comfortable with. I haven’t done this much, but there are some massive tomes that you can buy with table after table of ideas to help get the imagination going. I’d have to ask someone else for recommendations if you’re interested.
There are solo rules for just about every RPG out there. There’s one guy on Drivethrurpg.com that’s made a business of creating solo rules for different games (Parts Per Million). I have picked up one or two of these. They help you adjust the rules to play the game by yourself. DM Yourself is the one I like the best. It’s focused on 5e, but I found it translates to other games.
There are Journaling games like The Wretched or A Time To Kill. Sean did a run through of the second game on his How 2 RPG channel on YouTube. These games give you propmts that you use to help you create the story.
There are also game books. These are like Choose Your Own Adventure, but you typically have a character sheet and roll dice. Depending on what happens, you flip to another section to see where the story goes. I have some Tunnels and Trolls games like this, but haven’t played them.
I personally like to solo through published adventures. Not everyone likes it because it’s tough to avoid spoilers. My style has changed. Initially I tried really hard to avoid the spoilers and run through the game as a player. It was fun, but wasn’t the right fit. Now I play a hybrid of prepping for a game and then running a couple of PCs through the scene. It’s like I’m GM for a while, then turn the tables and play through the scene as a player. My plan is to run the game for other players, so it’s a good way to playtest the scenes.
I hope this helps. Let me know if you have a specific play style you’re looking to emulate. I’ll see what I can recommend.