Would help if you can tinker the mechanics around a bit too, but basically yes.
Let me be a bit more specific however, we are talking about the actual mechanics. And you better be damn careful how you do it. As tbeard was saying, it's not something that has ever really been tested in the courts. If you do it and you do get hit, you better be able to prove that what you have is original material even though the concepts and mechanics are from another system.
Breaking my own rule...I'd like to point out a couple of risks.
The US Copyright office probably has the most succint explanation of copyrighting games:
The idea for a game is not protected by copyright. The same is true of the name or title given to the game and of the method or methods for playing it."
"Copyright protects only the particular manner of an author’s expression in literary, artistic, or musical form. Copyright protection does not extend to any idea, system, method, device, or trademark material involved in the development, merchandising, or playing of a game. Once a game has been made public, nothing in the copyright law prevents others from developing another game based on similar principles."
http://www.copyright.gov/fls/fl108.html
However, this statement could be misleading. The name or title of a game isn't protected by copyright, but *is* protected by trademark (a completely different section of the law).
So while you can recreate the rules to D&D, you'd better NOT name your game "Dungeons and Dragons" unless you yearn to get to know Hasbro's legal team... And in the RPG context, many things can be trademarked, such as titles of games, names for systems (like, for instance "D20 System"), names of monsters, etc. From the WOTC OGL, a list of things *not* covered by the OGL (and probably trademarked):
"Dungeons & Dragons, D&D, Player’s Handbook, Dungeon Master, Monster Manual, d20 System, Wizards of the Coast, d20 (when used as a trademark), Forgotten Realms, Faerûn, proper names (including those used in the names of spells or items), places, Red Wizard of Thay, the City of Union, Heroic Domains of Ysgard, Ever-Changing Chaos of Limbo, Windswept Depths of Pandemonium, Infinite Layers of the Abyss, Tarterian Depths of Carceri, Gray Waste of Hades, Bleak Eternity of Gehenna, Nine Hells of Baator, Infernal Battlefield of Acheron, Clockwork Nirvana of Mechanus, Peaceable Kingdoms of Arcadia, Seven Mounting Heavens of Celestia, Twin Paradises of Bytopia, Blessed Fields of Elysium, Wilderness of the Beastlands, Olympian Glades of Arborea, Concordant Domain of the Outlands, Sigil, Lady of Pain, Book of Exalted Deeds, Book of Vile Darkness, beholder, gauth, carrion crawler, tanar’ri, baatezu, displacer beast, githyanki, githzerai, mind flayer, illithid, umber hulk, yuan-ti."
In addition, while game rules cannot be copyrighted, I think that game settings should be copyrightable in the same way that characters and "scenes a faire" in novels can. I've seen no law on this (yet), but I strongly suggest that you don't lift the Greyhawk setting for your new game.
Also, as you noted, game mechanics (like many ideas) *may* be protected by patents. The good news is that patents are expensive to get and I am unaware of any patents for RPG rules. WOTC was awarded a patent on the collectible card game strategy (applied for in 2002; announced in May, 2007). However, the award of a patent only creates a presumption that the patent is valid. This presumption can be overcome if the defendant can produce sufficient evidence that the patent is invalid. I have not heard that WOTC has sued any other CCG manufacturers (yet).
A very interesting experiment going on right now is OSRIC which is basically an OGL version of AD&D. It is based on the d20 SRD only where they felt they couldn't directly based it off the original AD&D system. Which goes to my point about something released as OGL that might have potential problems if WotC decides they want to challenge it. If I as a publisher chose to produce material using OSRIC and WotC later decides to challenge it and does manage to win, they could and likely would force me to recall any remaining books in the distribution channel (which I would have to refund) and destroy the remaining stocks.
In my opinion, anyone who relies on an OGL has an affirmative obligation to comply with its terms. The WOTC OGL explicitely address this point:
"If You are contributing original material as Open Game Content, You represent that Your Contributions are Your original creation and/or You have sufficient rights to grant the rights conveyed by this License."
So, the (example) OSRIC people are agreeing that they will only license material that they have the legal right to license in the OGL.
"You agree not to Use any Product Identity [i.e., things not covered by the OGL], including as an indication as to compatibility, except as expressly licensed in another, independent Agreement with the owner of each element of that Product Identity."
Here, the OSRIC people are agreeing to not use non-OGL material in their product unless they have the legal right to do so.
In my opinion, it's incumbent on anyone who relies on *any* licensing agreement to understand its terms and conduct reasonable due diligence to determine if the licensed material is, in fact, owned by the licensor.
I think I now understand your concern, Hunter. The OGL may be a wonderful thing, but it is still a serious legal contract. Unrepresented non-lawyers should always be careful when relying on such contracts. And while game companies will typically have experience with contracts (and lawyers to review them), casual gamers probably won't. In that case, caution is warranted. At the very least, a gamer should NEVER assume that everything in a work is Open Content. The most sensible (and safe) approach is to assume that *only* material in the SRD (referenced by the OGL) is Open Content. And, of course, OGLs may vary; be sure to read the one that's applicable to your situation. (Mongoose uses the Wizards of the Coast OGL).
Anyone who wants to publish something should probably allocate some money to get an opinion from a lawyer...
If I were a betting man, I'd wager that the OSRIC folks will not run afoul of WOTC unless they do something really stupid, like use trademarked terms that are not covered by the OGL.
It is interesting that Kenzer & Co chose to explicitely license the AD&D system from WOTC when they published Hackmaster. I suspect that they did this so that they could use AD&D text, images, and terms verbatim without worry. If they didn't, I think that WOTC could have made a strong case for both copyright infringement and trademark infringement (if they desired to do so).
AThat won't help if your company is based in a country that honors and upholds copyright law. But it is often much cheaper to have it printed there and shipped here than to have it printed here!
I'd add that unauthorized distribution of a copyrighted work is itself a copyright infringement, subject to the copyright laws of the jurisdiction in which the work was distributed. So printing the work in China won't help you if you distribute it in the US.
[Mandatory CYA disclaimer]: I am a lawyer, but I'm not YOUR lawyer. What I post in this forum is not legal advice and should not be relied on by anyone. Any legal opinions or information that I may publish here are exclusively for purposes of entertainment. No reader should ever rely upon any legal opinions or other information published here — not even just a little bit! If you need legal advice, HIRE A LAWYER. duly licensed to practice law. I don't even pretend to be as careful in what I may spout off with here as any lawyer must be in advising and representing real clients.
