In an alternate world where fantasy is alive and magic works, there exist numerous enchanted tunnel complexes (call them dungeons if you wish) that are liberally loaded with many types of treasure, and abundantly guarded by every imaginable form of monster, magic, and trap. Brave men and women of many different kindred (humans, elves, dwarves, hobbs, leprechauns, and many others) arm themselves and venture within the tunnels at risk of body and soul to seek treasure and experience. Those who survive and return from such expeditions increase in power and wealth to great heights of glory over a long period of time. Every time your character returns from a tunnel alive (or any kind of adventure—you need not be underground), you may consider yourself a winner. The higher the character level and the more wealth your character attains, the better you are doing in comparison to all other players.
What the Library has:
Take The Money - Condensed rules for Tunnels and Trolls, including a GM adventure