My output for the 2300 AD universe—entitled Operation: Back Door—was originally slated to be a stand-alone product, but for a whole host of reasons, ultimately came out serialized in Challenge magazine, no.s 49-52, (1991). It’s still available as a collector’s item, and is bundled on cd-collections of GDW’s rpg gaming material.
I feel that, in a variety of ways, 2300 AD could legitimately vie for the title of “The Best SF RPG Ever Produced”. Growing directly out of the shattered alternate-history of Twilight 2000, it embraced rigorous planetary science and utilized genuine star charts (the Gliese 3 data, if I remember correctly) to build the campaign map which indicated where and how humanity was spreading among the stars. Alas, the rules of play weren’t that well received—but the strength of the vision which built the universe clearly transcended that factor, since 2300 AD endured to become one of the settings supported by Steve Jackson’s GURPS system.