Dougi has a set of adaptations for solitaire play of the popular commercial set of rules Song of Blades and Heroes.
Rules: Fantasy
Dungeon Tiles To Print and Play
Quests of Legend has a nice collection of dungeon tiles for you to print out and use for your role playing or miniatures games (or both!) in a dungeon crawl.
Dungeon Delvers Rules
Dungeon Delvers is a set of free dungeon crawl rules.
Song of Blades and Heroes Solo Rules
Here are some interesting thoughts on playing Song of Blade and Heroes solo.
Isildur’s Bane Solitare LotR Battle Game Rules
Isildur’s Bane is a set of free wargames rules for playing solo games of the Lord of the Rings Battle Game.