If I wanted to make a game based on Lovecraft's fiction, could I do that? Or are his stories still covered by copyrights? What about trademarks and such, such as Call of Cthulhu? Can I make a Lovecraftian roleplaying game called Call of Cthulhu and get away with it?

What about the creatures, gods and other beings? Can my game include Deep Ones, Nyarlathotep, a town called Insmouth and a book named Necronomicon?

Where would I turn to learn more about this, assuming my book is published in the US.

Thanks. 

I don't know much about love crafts fiction but you can check the intelectual property section of this article http://en.wikipedia.org/wiki/H._P._Lovecraft

My personal judgment is that much of Lovecraft is available for me to do with as I will. Currently my own design ambitions are not bounded by Lovecraftian copyright considerations. The American copyright law is more complex, though, and has longer protection periods - all of Lovecraft became clearly and uncontestably public domain here in Europe just this year, while a similar turn in the US is still something like 15 years away.

The problem for USA is that your copyright law is marred by some pretty complex practical research questions, which means that hiring a lawyer to answer this question could be prohibitively expensive - such a lawyer would have to explicitly research several publications made long ago to find out when they were published, who they claimed copyright for, whether those copyrights were ever reneved, and so on. Wikipedia and most other sources seem to claim that the Arkham House copyright claims are fictitious (perhaps based on just such research), but apparently the company is confident enough in them to make noise now and then. Asking them about it informally is not useful, because it is in their interests to lie outside courtroom about the strength of their evidence to dissuade potential contestants - which means that the only way to find out the real state of the Arkham House copyrights would be to provoke them into taking you to court about it, where they would have to prove or fail to prove their claim. My personal feeling is that Arkham probably would do nothing at this late date against you, and if they did, their claims would not stand up in court, but I'm not Arkham, and not the court. Anybody can sue anybody for anything, practically speaking.

I'd say that probably your biggest concern in this regard would be Chaosium, as it probably has a bunch of trademarks related to Lovecraftian concepts. As long as you don't run afoul of those, I find it unlikely that any of the other usual suspects would file any claims. So if I were publishing a Lovecraftian rpg in the US, I would check what trademarks Chaosium has on the topic, name my game something that doesn't infringe on those, and then go wild with the contents of the game - dreamland, Deep Ones, Arkham, whatever I wanted to include.

Also note that people have been creating Lovecraftian rpg materials in increasing numbers lately with no problems.

Hmm... if I were worried about this sort of thing, perhaps I'd ask about it from Arkham House. Who knows, they might just say that they don't care if you do create something like this. Whether this'd be because they've decided to not press their claim on Lovecraft copyrights anymore, or because they consider you insignificant, doesn't really matter, does it?

I don't think you would run into much trouble utilizing the same races and specific entities by name.  However, for safety and out of general respect (not to mention to prevent appearing unoriginal), I would definitely refrain from calling the game "Call of Cthulhu."  We all know what comes to mind when you hear that name and it won't do your game any favors any more than a fantasy game by yours truly which I decided to call Dungeons & Dragons or RuneQuest would do for mine.  That's my basic rule of thumb, anyway - stay away from using the same title as a well-established institution.  That said, I'm not a lawyer and this advice is worth what you paid for it.

Peter, the person to ask would be Simon, who publishes Trail of Cthulhu. I'll point him over here.

Graham

I don't actually know that much about it.

I decided to approach Chaosium for a license, partly because we specifically wanted to do an update of Cthulhu for GUMSHOE, partly out of respect for Chaosium and CoC fans, and partly to cover us against possible trademark or copyright infringement. If we hadn't been granted permission I would have gone ahead with a very different Lovecraftian horror game based on our best understanding of the trademark and copyright status of his works. I suspect the risk is low, but I receommend you consult a lawyer

I'm in a similarly complex position with the estate of Conan Doyle - you'd think it was straightforward, but trademarks get in the way of what is apparently freely available.