I don't know how people access Itch reviews so I'll leave this here:
If you're interested in sologaming you've got to give this a try. It is the full Unfolding Machine, so it might look a little overwhelming -- but it has several different *modes* that facilitate all kinds of different methods of play.
It's a Co-GM, it's a Solo VTT, it can play my most complex games and allow me to play it alone with ease. PUM Companion settles the chaos of my mind, its got a pretty detailed manual and tutorial built into the app to get you going a bit and an active community to help.
It gives you a guided setup to place your preferred game or world into it's different moving parts and custom tables too, so if you have some favorites you want to bring in from your favorite solo tool.
THE solo gaming environment in my heart.