Their innovative game system requires a single d20 to play, a pencil, and something that acts like a calculator (there is after all, an app for that) and a sheet of graph paper usually helps. The d20 Only Rage Series system allows for quick results and an end to tedious hour-plus long Combat round during game play. Let your adventures get back to the adventure! With the d20 Only Rage Series system, there's no more hour-plus long combat rounds. Game play is quick and lets you get back to the basics of story-telling and adventure!