From the introduction: Welcome to the G.I. JOE d20 Role-Playing Game. Here, players can assume the roles of top soldiers joining America's elite counter terrorist-force, G.I. JOE. If the GM allows it, players can opt to join COBRA, a ruthless terrorist organization determined to rule the world. This game is a setting, and uses the d20 Modern system. User summary: This fan-made game adaptation of the toy and media franchise uses a lightly modified d20 Modern rules system.