Flying Buffalo Inc (FBI) has been running play by mail games since 1970, and publishing war games, card games and role playing games since 1975. We recently did a very successful kickstarter to create a new "Deluxe" version of our RPG Tunnels & Trolls, which is available here. One of the things T&T is famous for is our extensive line of SOLITAIRE adventures, where the book leads you through an adventure. We were the first to produce a solo adventure for an RPG (Buffalo Castle, which is available here).  Don't forget our GRIMTOOTH'S TRAPS books. There are seven of them.