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I've got an expansion for a semi-popular board game that my friends and I have been having a lot of fun with. I was wondering if I could package and sell the expansion to the game without consent from the original publisher. I know I'd need to create all of my own materials (artwork, text, etc.) but I wasn't sure if I could market it as "Third party expansion to X".

Are there any pitfalls I should be wary of? I don't want to rip off the company or cause problems with them, but ideally I wouldn't need to have a lot of contact with them either (since they may not like it, even if it is perfectly legal.)

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up vote 3 down vote accepted

There will be very different answers to your questions depending on where you plan to sell your expansion. I think Europe in general is much more restrictive about mentioning trademarks without explicit permission than for example North America. You'll probably want to consult a lawyer before going ahead with this.

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My guess would be that in the US, as long as you don't imply that the manufacturer authorized it (I'd go with 'The unauthorized expansion to...' in my title), you'd probably be ok, legally. But remember, even if you are within the letter of the law, they still might sue you, and you'd still have to defend. I'd check out the manufacturer's history of legal action to see what you might expect. – Michael Kohne Jul 11 '11 at 20:13

0) I am not a lawyer. I am definitely not YOUR lawyer. I don't even play one on TV.

1) go read the circular on Trademark at the website.

2) Realize that, if you aren't in the US, you need to find the equivalent for wherever you are.
Canadian IPOUK IPOFrench IP Agency
Directory of Intellectual Property Offices

3) Realize that anywhere you intentionally sell it, you have to obey their trademark laws, too.

4) before doing anything commercially, hire a lawyer specializing in intellectual property law, and have him go over the risks and requirements with you.

Fundamentally, a 3rd party supplement can't use the distinguishing marks of the core game (TSR v. Mayfair), and can't use the unique phrases associated with the game, either. The closest I've seen to doing so that wasn't challenged nor licensed was "Not a complete game; requires the use of n, by n." and "For use with n and other n games."

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The artwork and language may be copyrighted so at a minimum you'd have to create your own.

What you should do is call them up and see if they are willing to license their product.

Some will, some won't.

Here's one good link.

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"The artwork and language may be copyrighted" - actually, they definitely will be copyrighted, absent some really weird situation like a game published before 1973 by a company that went out of business, or made entirely with public domain art. – Mark Bessey Jul 15 '11 at 23:32
+1 I really like that link. It does a good job of describing what you can do legally, but also the problems with a larger company threatening legal action even if you are within your legal rights. – Chris K Dec 20 '11 at 4:27

Back in the 90's, I remember seeing (and purchasing) several "unauthorized" expansions for Axis & Allies at GenCon. Some even had brand new plastic molded units. I can't imagine that anyone would go through that level of effort (both in quality and in renting a booth at GenCon) on an unauthorized expansion if they had any thought that MB/Hasbro would sue them. So as long as you give credit to the company that makes the game you are expanding and (as others have said) don't use any of their artwork, you should be fine.

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