from the RPG description
Tunnels & Trolls was the second RPG ever published. Author Ken St. Andre found a copy of D&D and decided it was too complex for his tastes. T&T was the first RPG designed with simplicity in mind.
The first four editions were all solely authored and self-edited by Ken St. Andre. They differed mostly in format, cover, and a growing body of creatures and actions rather than changes in rules.
The fifth edition was edited by Liz Danforth and marked a significantly different expression of the game, and so has its own entry. However, all T&T supplements from all eras work with any edition.