I sometimes have trouble finding people who are available to play RPGs with me on a regular basis. When that happens, I turn to solo RPGs. While they are more prevalaent than they used to be, it's still kinda tough to find them. Tunnels and Trolls is one of the best ones I've found so far. It isn't hard to learn. It's a bit like a 'choose your own adventure' book, but even more fun since you can level up your character, customize what he carries and sometimes make decisions that are more than 'do this or that'. I highly recommend any of the T&T books. Whichever ones you get, you really ought to get this rules book to go with them so that you get the full experience.
[5 of 5 Stars!]