From the back of the book: The year is 1910. It is an age of crumbling empires, dangerous adventures, and rotting decadence. Rifles crack across the untamed Khyber pass, sorcerers stir from eldritch crypts, and dark things dream and lurk in secreted, fetid corners of the globe. Raiders of R'lyeh is a stand-alone roleplaying game and sourcebook in which mercenary rogues explore forbidden frontiers, unearth ancient artifacts, and outwit villainous scum. Derived partly from classic 1d100 rules that have been released under the Open Game License, the game is crafted to emulate not only adventure in the Cthulhu Mythos of H.P. Lovecraft and his circle of influences, but especially the savage and evocative feel of Robert E. Howard's Mythos and Weird menace stories.