I play a lot of solo wargaming. Two names above all: Mike Lambo and Tiny Battle Publishing. Now I'm trying a new approach:
1. Rather than playing against a Pen and Paper AI, playing against myself. Some people don't appreciate this practice but, to me, it seems very natural: it's about conceiving the match as an experiment aimed at determining which warband is stronger with the same decision maker. (which is always you of course)
It doesn't make sense with games that include secret choices but many don't have them or provide the possibility of removing them.
2. I'm getting into skirmishes (few pieces and high level of detail) and I've started to wonder if the old role-playing game rules aren't more suitable than skirmish wargames themselves....
In particular GURPS Man to Man (perhaps with the addition of some wizards) or Rolemaster.... perhaps in its more modern incarnations such as Against the Darkmaster or Fantasy Express.
So I decided that, once I've finished the MapTool module to play Fantasy Express, I'll try it as a solo wargame. At first in me vs me mode and then, if I can, I'll write a little pen and paper AI.