I want this list to be a useful collection of games that either work great as solitaire experiences, can be played with just one or two players and a gm, or can be played cooperatively with the gm as a player character as well.
Another 2-player geeklist, with a specific interest:
The list should include role-playing games (not gamebooks) that satisfy one of following conditions: - explicitly list "two" as a number of players suitable for this game - have a special chapter in the main rule book about playing the game with two players - have an official supplement rule book - not an adventure/module - describing how the game should be tweaked to accommodate two players (in this case the RPG Item for this supplement must be added, and not the core book).
If neither of the above conditions is satisfied, the game should not be added. Even if it: - plays very well with two - can be tweaked to be playable with two - some guy posted in his blog his house rules to play it with two - has published adventures for one GM and one player - has solo adventures that can be tweaked to be played with two etc.
The main idea behind these conditions is to find games that were specifically designed with two players in mind or have official two-player add-on rules.