I'd've said 'd20/d20-derived-OGL gamer' if that was an option. Which covers 3.x D&D, 4e D&D, SWSE, d20 Modern, and a d20 Modern / SW RCR hash-up at the tabletop, adds d20 Wheel of Time and M&M 2e in PBP, and counts the copies of AU, Blue Rose, True20, CoC d20, and Iron Heroes on my bookshelf of unplayed games...