The way I see solo RPG engines is that they fall into three classes. I have just finished writing my submission for Angela Quidam’s 5-minute game jam.
This is a simple game, ask yourselves some questions and then write, for 5 minutes, about your character’s story. No more, and no less. Thus the 5 minute game jam.
Many games have this question and answer format. Wretched games combine a deck of question cards and the jenga tower. Descended from the Queen is a solo system the all builds up to answering one big life changing question.
These question style games are rich in theme and style, but lose out in the replayability.
The second pool of games are dice based engines. I wrote about an idea recently in my Red vs. Blue post. Red vs. Blue is an incredibly basic game idea, but anything can be built up and extended. This is a game that was built to be solo right from the start, from the ground up.
The difference between a dice based solo rpg engine and a question based game is that the solo story is driven by the random nature of the dice rolls. You are still going to ask questions, but they are your questions not ones written by the game designer. If you want your game to go in a specific direction, your questions will shape the game.
Diced based systems can be as simple or as sophisticated as you want. CRGE is a long-established dice engine system along with BOLD, UNO, and TOSS.
I cannot possible mention every great dice based system. There are so many of them. Each will give you something unique. I find the deciding factor is the amount of dice rolling involved. I am not a fan of too many dice rolls. As you evaluate dice based solo games, you get to choose how much is too much, or how much just enough.
Integrating Solo Systems
Solo RPG engines can be as simple as Red vs. Blue or as heavy weight as Mythic GME or even Ironsworn. Under the hood you are still rolling dice to answer questions you asked.
A dice based solo rpg engine can be bolted on to any game. This is what I do most days. I start with the games most influential dice mechanic and work out my yes-no rolls from there. Then I try and fold in all the best bits of the system.
Ironsworn is not a bolt-on. The game was built with both solo and group play as central design criteria. I put Ironsworn into this group because the game engine is open for other people to hack. There are loads of derived games from Atomsworn and Iron In The Blood. There are even official derived systems out or in progress, like Delve and Starsworn.
Soloing for our Hobby
I am not a massive fan of the question based solo system. The reason is that they lack replayability. What I like is being able to play and replay. Try out different characters, different situations and even different characters in the same story. I cannot do that inside these question stories.
What I want to see more of, are games like Ironsworn, where the solo rules are there for the GM to read when they buy a new game. As a GM with a new system in hand we nearly always make a few characters to get a feel for the system. If there are rules on how to play the game, right there, ready to play. I can see more GMs just trying out a little bit of solo play, just to get a feel for the game.
If that happens then solo play will become more common, more accepted and more normalised. And that has to be a good thing.