Chaosium

From Chaosium’s Web-Site:

The Chaosium was founded by visionary game designer Greg Stafford in 1975.

"The first published RPG was Dungeons & Dragons, shortly followed by some other imitative games. Chaosium, however, was never content to imitate but published games that were original in style of play, content and design. We quickly became renowned for our originality and creativity, and were responsible for introducing many things to the hobby that are standard today." - Greg Stafford

The roleplaying games RuneQuest, Call of Cthulhu, King Arthur Pendragon, HeroQuest – as well as such classic board and card games as White Bear & Red Moon (later called Dragon Pass), Nomad Gods, Arkham Horror, Credo, and Mythos all originated at Chaosium.

Many of Chaosium’s product lines are based upon literary sources. Most notably, H.P. Lovecraft’s 1920’s horror fiction provides the basis of our Call of Cthulhu roleplaying game line. The Lovecraft Cthulhu Mythos also provides the inspiration for many of the books in our Chaosium Fiction line.

We also publish Basic Role Playing (BRP), the core of our roleplaying game systems, and the first to use skills based upon the d100 mechanic. Call of Cthulhu, RuneQuest and most of our other RPG lines use BRP as the basis of their rules. Once you’ve learned to play one of these, you've learned to play the others.