Complex sentence: The "BRP" was the RPG industry's first attempt at a truly generic rule system, preceding "GURPS" by six years and the "d20 System" SRD by nearly twenty.
Split into simpler sentences: The "BRP" was the RPG industry's first attempt at a truly generic rule system. Something that preceded "GURPS" by six years and the "d20 System" SRD by nearly twenty.