... each player should possess a personal 20-sided die. The die is used to resolve combat, make skill rolls, and so on. Sharing a die is fine, but it’s weak magic. In Sword & Backpack, dice aren’t just tools, they’re a direct line to fate, a link to the great mystery. As such, they should be respected. Your personal die should be carried in one’s pocket at all times. It’s a totem. Respect it as such.Emphasis mine.
You can find a primer on, and links to, Sword & Backpack here. S&W is a tongue-in-cheek presentation of the simplest RPG rules imaginable. Basically roll a d20 and see if it's high or low, and how high or low. Sounds simplistic, sure, but what more do you really need? Also, the formatting of the rules is kind of cool; the small pages are meant to be printed, cut out, and pasted into a 3.5" x 5.5" (or thereabouts) notebook.