From the introduction: Halo: The Covenant War is a tabletop RPG based on Bungie’s Halo series of FPS games. It uses a variant of Fudge, a free system created by Steffan O’Sullivan. The complete rules are included here, but if you’re interested in finding out more about the system and its endless options you can get it online, or there’s a print version published by Grey Ghost Games. I went with Fudge basically because I’m intimately familiar with it and know how to make it do what I want. Character creation is radically changed from any existing Fudge variant, and the default wounding rules are replaced with health points. For more on Fudge, check out www.fudgerpg.com; there are zillions of different variant rules that could be plugged into this game if you’re so inclined, especially in the hardcover Fudge 10th Anniversary Edition.