The only specifically solitaire one I can think of is D-Day Dice.
Memoir '44 can be played solo, although it's not designed for it.
I own both of these and would definitely recommend them. D-day dice if you like rolling tons of dice and then manage resources. Memoir 44 if you want a more tactile hex war experience (there are several solo variants that work well). My current solo variant is to hold up 3 cards for my two year old to choose one and then I preform that as optimal as I can for the opposing side lol.