D100 Dungeon is a print-and-play solo game of dungeon crawling. It involves a 53 page book (your laser printer can easily handle it), and uses a series of tables to guide you through an adventure.
D100 Dungeon is a print-and-play solo role playing game of dungeon adventures.
Ada Lovelace: Consulting Mathematician is solo roll-and-write game. it is offered on a pay what you want basis.
1972: The Lost Phantom is a free print and play solitaire game about an F-4 pilot shot down behind enemy lines in Vietnam, trying to find his way back to safety.