That would be the Dark Adventure Theater Radio adaptation of The Call of Cthulhu, and I hadn’t gotten that one yet. Which is nice: nine times out of ten, when I see one of these specials or giveaways it’s for something that I already own, so I can’t take advantage of it or anything. Mind you, the physical CDs typically come with physical props that could be used in later gaming — HPLHS is absolutely aware of the various Call of Cthulhu RPGs — so I may pick up one later anyway. But for right now I can still listen to it.
They’re doing it for Lovecraft’s birthday, so get it soon.