Does anyone know the legality issues surrounding publishing supplements for existing games?  I was thinking about creating a naval supplement for tabletop wargame.  I'll be trying to sell it to the company that created the game first, but should that not work, I was thinking about producing the book myself through POD companies.

Similarly, I was thinking about creating additional units for an existing wargame and I'm considering making a book out of them as well, 

I'm not a lawyer so everything I'm about to say is probably meaningless.  It is my understanding that unless the "existing game" in question has an OGL (open game license), and you somehow work within those confines inherent in the OGL or get express permission blah blah blah, publishing "supplements" for an existing game will get you sued for copyright infringement.  If you want to change/add stuff to an existing game, go work for that game company or create your own game independent of said existing game company.  In terms of publishing, any responsible publisher POD or otherwise is going to require that you have a right to or ownership of any material submitted for printing/publishing.  Since you don't, you can't.  Well, you could until you're sued, finacially ruined, and/or go to jail. 

Wizards of the "destroy every game they takeover because they are a bunch of fucking dousche bags", as in D&D, sued Paizo for publishing Pathfinder.  In some kind of legal agreement, Wizards of the Assholes and Paizo arbitrated an agreement and Wizards of the Craptastic created an OGL for certain aspects of the game (specifically mechanics).  Games Workshop will come after you too.  Don't think there is an OGL for them. 

If I ever publish a game and you started making "supplements" or "additonal units", your great grand children will still be working for my great grand children to pay off the debt, if not insolence. 

In closing, don't do it or apply for a job with the game company (but they will own the material, not you). 

Late...

Hi Grigori,

To my knowledge Paizo was never sued by Wizards of thge Coast. The OGL actually was released years earlier as a part of the D&D 3rd edition rollout.

Paizo was born as a company headed by Lisa Stevens, the very first employee at Wizards when it was first getting started, and it began by taking over pubications of the entire Wizards magazine publishing department, including assuming all of their overhead and employees, when Hasbo was looking to shut down that department.

Ok, that being said, publishing a product "for" another game has these issues:

1) Without a license you can't use any of their copyrighr protected text (which would be just about all of their text) nor make any reference to their Trademarks. This alone will make it very difficult for your product to draw a proper association to the original product and thus its fans.

2) While the text of a game publication and its trademarks are both protected, strictly speaking, the "game mechanics" themselves are ideas and therefore not protected. However, to access the use of those game mechanics without violating any of their copyrights would mean finding a way to completely rewrite and explain all of those rules yourself, without drawing from their original text or duplicating any of that original text. That in itself can be a challenge and to avoid a lawsuit.

3) When producing a product that is to be used "exclusively" with another product, even should you avoid all the copyright and trademark pitfalls and find a means to associate your product to the game and the fans of the game for which your product was intended, being a product completely dependant on the original manufacturer's product might still mean your product could be declared a derivative works and you could become legally liable the same as if you had actually vilated copyrights and trademarks.

The Guild of Blades has successfully published many "Axis & Allies" variants, a "Talisman" variant, a couple "Risk" variants and a "Titan" variant over the years. But none of these games were designed and intended to be "for use" with any of those original games, but were rather complete games upon themselves and they avoided the copyright and trademark traps. That said, we were also challenged legally initially in a couple of those cases, but as our ducks were in a row those challenges could not proceed any further.

The usual caveat applies. I am not a lawyer and if you think you might want to pursue this, a consultation with an intellectual propperty lawyer is advised.

Ryan
GOB Publishing