A long time fan of Lovecraft and the Mythos, I also happen to prefer simple systems when it comes to running games. I've tried several --- then recently stumbled upon The Black Hack, a fast play Old School retro-clone (to use the technical term).
The Cthulhu Hack is a role-playing game in the fine tradition of the classic Original 1970s Fantasy Roleplaying Game but based on the hugely popular modern OSR clone The Black Hack.
The Cthulhu Hack summons and binds the fast play potential of the original, and adds in new elements to handle character investigation and the sanity-shattering shock of dealing with Things Best Left Unknown. It uses The Black Hack's elegant Usage Die mechanic to emulate the dwindling investigative resources available to those intrepid sorts willing to put their lives and reputations on the line in pursuit of the Unmentionable and Unthinkable.
Includes Lovecraftian monsters and a Mythos 101 for those unfamiliar with the original tales.
This is a standalone product, including the Open Game License material of The Black Hack.
Available now from RPGNow.