It's been regularly noted that the current old school renaissance would not have been possible without two things: the Open Game License and the Internet. I think this observation is dead-on and goes a long way toward explaining why the OSR is so strongly focused on Dungeons & Dragons rather than other old school games. Before I come back to that point, though, let's think back to the early 90s and the Dawn of the Wired Age.
In those prehistoric times, not one but two different old school RPGs experienced brief renaissances of their own, thanks to the increased communication made possible by the Internet. These RPGs were Traveller and RuneQuest. I was personally involved in the Traveller Renaissance, writing my first professional gaming articles and products during this time. I participated in online discussions on GEnie, joined the then-new Traveller Mailing List, and signed up with an organization of Traveller fans called the History of the Imperium Working Group, with whom GDW sometimes consulted when creating new products and from whom they drew when looking for new writers. Fanzines and third party licensed support for Traveller flourished. It was, frankly, a great time to be a Traveller player and an even better time to be a creator of material for use with Traveller.
Alas, the Traveller Renaissance proved to be an Indian Summer rather than a new Spring. A new creative team and a new direction from GDW threw a wrench into most of the existing fan and third party support for the game. HIWG and similar groups were sidelined or ignored entirely and communication between GDW and players became much more one-way. I don't blame anyone at GDW for these changes and, in many cases, I understand and even agree with the logic behind them. But, speaking as a fan and budding creator, it was very disappointing to see how quickly the winds had changed and how their doing so drove many of my friends and I away from the game. Nowadays, rather than being the premier SF RPG, Traveller is, at best, an also-ran.
In the 90s, RuneQuest (and its setting of Glorantha) lay in the hands of Avalon Hill and, by most accounts, they'd been badly mismanaging the property. Correcting course, RQ veteran writer Ken Rolston was made line editor of the game (or "Rune Czar," because, in the 90s, if you wanted to show you were serious about something, you appointed a "czar" to oversee it). Contemporaneously, the RuneQuest Digest, a mailing list for discussion, saw an upsurge in interest, as more and more RQ fans connected with one another through the Net. Under Rolston, Avalon Hill produced a number of highly regarded supplements to RuneQuest, often written by active and knowledgeable fans.
As with Traveller, there was a sense that RQ had turned a corner and that a true renaissance for the game was under way. Again, as with Traveller, this proved short-lived. Rolston left his position as line editor in 1994 to work on computer games. A falling out between Greg Stafford, creator of Glorantha, and Avalon Hill resulted in confusion for fans, as Stafford talked of creating a new, non-RQ RPG for Glorantha and AH talked of creating a new, non-Gloranthan RuneQuest. Another Indian Summer ...
What happened? Why didn't those earlier old school renaissances take and what does this mean for the current one? Well, from my perspective, the big difference between those earlier renaissances and the one happening right now is that they had the Internet but not the Open Game License. That is, both Traveller and RuneQuest remained wholly the property of their creators/publishers. When they decided to pull up stakes and change direction, there was nothing the fans and amateur creators could do but roll with the punches.
I'd also suggest that there's another factor at work here. Although both games could be treated as generic rulesets, they rarely were in practice, being instead heavily bound up in the example settings associated with them. Both the TML and RuneQuest Digest, for example, were generally focused on discussions of setting rather than rules. This fact, I think, colored the nature of those renaissances and made them more dependent on their origin points, namely the "official" game and whoever it was that currently held the rights to it.
Nowadays, the rules to both Traveller and RuneQuest are open game content, with RQ having, depending on how one counts, at least three different versions available for third parties to use in their own products. So far as I can tell, though, neither game has yet managed to engender another renaissance associated with it. There are probably several reasons why this is the case, but I think there are two big ones.
First, as I just noted, both Traveller and RuneQuest are much more strongly associated with their example settings than D&D ever has been. As an experiment, grab a random player of either game and start chatting with him about it; odds are very good that, before too long, the discussion will turn to the intricacies of the example setting rather than the game itself. That's much less likely to happen with a random old school D&D player. Second, despite being Open Game Content, there remain official rulebooks for both games, something utterly lacking for old school D&D. There's thus, at present, not a lot of incentive for a third party publisher to put out its own version of one of these games -- Voyager or SigilQuest, say -- and that has, I think, kept the focus on the official lines rather than a flowering of third party support as we've seen in the D&D-focused OSR.
None of this is to suggest that there couldn't be Traveller or RuneQuest renaissances in the future -- I hope there are! -- but, right now, if they're happening, they're happening very quietly and well off my radar. I'll grant I'm not as plugged into either of these games' online communities as I am with that of D&D, but neither am I unaware of what's happening in them. I keep hoping that I'll learn of the launch of a new Traveller fanzine or see some generic supplements to RuneQuest, but, so far, no such luck. I think that's a real pity, because, truth be told, I'd love to see a fuller flowering of old school gaming than just the very D&D-centric OSR. The fact that we don't, however, isn't the fault of the OSR; as Rob Conley regularly points out, the OSR is what its participants make of it and, right now, there's not much interest in making it about anything other than D&D and related games. If someone would prefer a wider representation of old school gaming, it's up to them to see that it happens.
The tools are there but is there the interest? Only time will tell.