From Martial Arts Mayhem, Volume One Introduction:
Welcome to Martial Arts Mayhem, a supplement from The Game Mechanics for the d20 Modern Roleplaying Game, full of off-the-top-rope, flying side kick, no-holds-barred action! When you use this supplement, every melee combat is unique thanks to added customization. Your heroes are no longer limited to the Brawl feat tree, the Combat Martial Arts feat tree, and Defensive Martial Arts. Instead, your heroes can become light-fingered masters of the Deft Touch School. They can confuse and befuddle opponents as masters of Drunken Fighting. Or they can launch powerful, lightning-fast kicks as masters of the Northern Leg School.
And because anyone can be members of these schools, your heroes will never know if the old man sweeping the sidewalk is a mere shopkeeper—or a secret master of Sticky Hands! Even when he takes his combat stance, they cannot be sure whether he knows the Thousand-League Eye technique, or Repulse the Monkey (or both) until it’s too late.
Martial Arts Mayhem maintains the balance between firearms and martial arts found in the d20 Modern Roleplaying Game. We designed it to work with the feats in the d20 Modern Roleplaying Game, not to replace them.