I wonder why?) and because I think Zebulon's Guide offers an interesting example of how fads can affect even game designers. Written by Kim Eastland and Bruce Nesmith, this book was ostensibly a supplement to TSR's science fiction roleplaying game, Star Frontiers. In reality, though, it was in fact a massive overhaul of Star Frontiers, changing nearly every aspect of the game to the point where I consider it a reboot rather than a revision (and certainly not a "streamlined" one, as claimed in the preface).
Back in 1985, a mania for color-coded action resolution charts had overtaken the hobby. Numerous games, such as Marvel Super Heroes and Chill, to cite just two with which I was intimately familiar, used such charts and I'm guessing that they proved very popular not just with players but with designers. I say this because it wasn't long before it seemed as if every RPG had action resolution charts of some sort, including some that hadn't originally included them, such as Gamma World and Star Frontiers. Zebulon's Guide was where Star Frontiers made its ill-fated transition to the world of action charts. I say "ill-fated" because Star Frontiers didn't survive the transition. Zebulon's Guide was the last supplement to the game and, while I can't say with any certainty that the rules change was directly responsible for this turn of events, I don't think it helped matters. TSR clearly intended there to be additional support for Star Frontiers, since Zebulon's Guide was released as "Volume 1," but no subsequent volumes ever appeared.
In addition to a new universal resolution mechanic, this book introduced classes -- "professions," they were called -- that worked in conjunction with a new skill system. The original Star Frontiers rules were skill-driven, it's true, but they were limited in number and utility, the assumption being that a lot of actions didn't require explicit rules to cover them, leaving their adjudication up to the referee. Zebulon's Guide changed all that by presenting us with skills for nearly everything. The skill list was huge, larger than Traveller's and fast approaching that of Space Opera. I don't necessarily mind lengthy skill lists; they can be appropriate to some games. However, the increase in the number of skills was such an about-face from what we'd seen in the original Star Frontiers that it made it hard to accept that this was somehow the "same" game.
Zebulon's Guide also gave us a fifth, optional profession -- the mentalist. The mentalist is a psionicist, using a variety of mental disciplines to achieve his ends. Again, I'm not opposed to psionics, especially in a sci-fi setting, but their introduction here felt "off." The original Star Frontiers gave no hint of the existence of psionics, at least not of the sort described in Zebulon's Guide. So their sudden appearance here, even as an option, further contributed to my sense that TSR was basically starting the game over again, extensively reworking what had come before into a new game. I was already at the time a big fan of Traveller, which was always my go-to RPG for "serious" science fiction; the appearance of Zebulon's Guide made it even less likely that I'd play Star Frontiers, since it meddled too much with the straightforward simplicity that made that game a viable alternative when I was feeling more "wahoo!" about sci-fi.
It's a pity, too, because there is some genuinely good stuff in Zebulon's Guide to Frontier Space. I loved the new equipment, the new races, and the expansion of the Frontier setting. But all of these things were lost in my mind because of the massive and unnecessary changes wrought to the rules and general feel of Star Frontiers -- all in the pursuit of the latest fad in game design. It's an object lesson, I think, on a game's staying true to itself regardless of what happens to be popular at the time. There's always room for experimentation and "innovation," but they're best reserved for new games rather than existing ones, a lesson contemporary designers looking to revamp classics of the hobby would do well to bear in mind.