Coming of Age
An uplifting game where you play people who are learning their potential and dealing with their issues in the midst of trouble. Create your own setting or use a setting sheet: Space Police Cadets, Squires of Sword and Sorcery, Scions of the Superspy. And yes, Coming of Age can be played solitaire.
There are only two important details about any Coming of Age setting. First, all the players must agree on the basic idea. Second, there must be a group in the setting who are in the process of coming into their own. Those will be the characters you will all play.