Jazz Core provides the basic rules for a generic, universal game system. It is assumed that Jazz Core will be supplemented with a "genre module" for Jazz of which several were contemplated but not produced beyond the starting stages.
Characters in Jazz are defined by Concept, Motivation, and Descriptors. It is suggested that characters have one Flaw. Health Points and Fringe Points also are determined. Each Descriptor has an associated Fiction Level ("Mundane", "Exceptional", "Elite", "Heroic", "Legendary", or "Mythic"). The Fiction Level determines how many dice are associated with the Descriptor. The first Descriptor is the Primary Descriptor--the broad, main character type; other Descriptors are Secondary Descriptors. Some characters will have Fringe Descriptors that allow them "powers beyond the realm of what most other characters can do". Characters also are assumed to have numerous Universal Descriptors which are things that "everybody" from their cultural period can do ("Drive a Car" or "Use a Telephone").
Combat is fairly abstracted with few modifiers. Damage is determined using d6; unarmed strikes do 1d2, frag grenades do 3d6. Armor reduces damage; thick padding -1, Heavy Assault Force Screen -10.