Not to burst anyone's bubble, but I ran into a similar problem several years ago.
I was making a computer game, from scratch, based on Avalon Hill's "Magic Realm" board game.
After mentioning it on several forums, and being asked about legallity, I contacted Hasbro, Avalon Hill's current owner, about it.
I was politely told, in no uncertain terms, that while they couldn't prevent me from making the game, they would sue the begezus out of me if I gave even one copy away for free.
I've heard tell that LucasArts has the same attitude about their properties.
While I was working on the "Privateer: The Reckoning" mod for Freelancer, I was told that as long as no money was involved, we were free to proceed.
(But I can't recall if that was official, or not.)