Years ago, George R.R. Martin’s “realistic” superhero series, Wild Cards was adapted for Steve Jackson Games’ similarly “realistic” roleplaying game system, GURPS.
In this brief interview, he mentions moving his own gaming group over from a hodgepodge of systems — Superworld, Call of Cthulhu, The Morrow Project, Paranoia, Dungeons & Dragons — to just GURPS 20 years ago: