I've heard Chaosium referred to as "the sick old man of the roleplaying industry." Best known for Call of Cthulhu, Stormbringer and other licensed games, Chaosium provided one of the earliest percentile systems for gaming.
RuneQuest, as the first Basic RPG incarnation was known, carved out a strong niche for itself, quickly gaining a reputation as being far more intuitive and easy to play than the most popular systems of the day (namely D&D and Traveller). The company licensed H.P. Lovecraft's mythos for the Call of Cthulhu RPG, easily Chaosium's most popular, and it's the longest-running game system published under the same owner.
Basic Roleplaying didn't stand alone. It was the house system at the core of most Chaosium games, which weren't all necessarily fully compatible, as variants developed to better serve different settings (such as more detailed rules for insanity in Call of Cthulhu as opposed to RuneQuest). Eventually, the variants were boiled down, re-edited, regurgitated, to form a GURPS-like generic system.
Several Halloweens ago I played my first Call of Cthulhu game at Pulp Fiction, with Jay Sprenkle holding the reigns. I had a good time, and picked up the book. Last weekend I finally got my chance to run a Call of Cthulhu game of my own with my regular gaming group.
We're all big Warhammer Fantasy Roleplay fans - back from the percentile days, no expensive custom dice for me, thanks - so the Basic system was easy to grasp. In fact, there almost didn't seem to be much to it. More than any game I've played in a long time, the rules seemed to fade into the background. Very little interfered with the fictive dream.
Some games change so much over time, the cynic in me wonders whether, in most cases, there is a sincere need to revise things that don't work, or whether new editions and rules changes are planned to come out every few years regardless of how well the system works. Hasbro, now producers of D&D, is especially bad about this, and now that Fantasy Flight Games has revamped Warhammer and Star Wars with custom-dice systems, I wonder how Chaosium has managed to stay afloat all these years with their system. I guess they designed it "right" in the first place.
Also, the new wave of tabletop games, exemplified by such systems as FATE and Burning Wheel, tend to elevate to full rules status (that is, mandate and spell out), subtle things such as character ambition and morality and what makes them special - all stuff that, to my mind, players have always been doing anyway. There's nothing wrong with codifying and encouraging that behavior, but I sometimes wonder if, by marrying free-form roleplaying to hardwired game mechanics, the new wave hasn't so much liberated or enhanced roleplaying as strangled it. I suppose it all depends on the group, the game master, and their personal tastes.
For me, the Basic Roleplaying system was a a breath of fresh air. Simple, direct, intuitive, easy-to-learn. Within 15 minutes our group was gaming it like veterans. While I am certainly not of the Bitter Betty School of Game Design that mars the so-called Old School Renaissance (that is, the assumption that everything created after 1980 is shit), it's nice to know that there are some systems out there solid enough to withstand nearly 40 years without much change. My guess is games change so publishers can sell new games, not because the rules need changing. I applaud Chaosium for not going down that road.
That being said, I believe the general graphic design of the company's products leaves a bit to be desired, but that's purely subjective.
Anyway, for you "old-school" gamers out there, remember that you're playing brand-new games designed to emulate old ones. That's awesome. But it ain't actually old. Looking at the history of RPGs as seen through the lens of D&D, I don't think anyone could successfully argue against the assertion that when it comes to playing "old-school," Basic Roleplaying is about as old-school as it gets. And in today's bevy of supposedly simple games that add layer after layer of complexity and special booklets, that's refreshing.