Solo gaming comes in all shapes and sizes. Today's shapes look like this :)
Attacks of Opportunity
Which morphed into this:
About How to Host a Dungeon
And if you have a few minutes to kill and want to do some crawling or even show someone new to the hobby how much fun they can have, just start them with this:
Solo Dungeon Bash
And with such a simple form you can re-load this a few times until a bigger challenge is desired.