I am occasionally asked about the rights for the systems used in Britannia. The following is from the government copyright site (retrieved 11 March 2006):
"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.
Some material prepared in connection with a game may be subject to copyright if it contains a sufficient amount of literary or pictorial expression. For example, the text matter describing the rules of the game, or the pictorial matter appearing on the gameboard or container, may be registrable."
[Emphasis added by L. Pulsipher]
As you can see, the ideas or systems of a game cannot be copyrighted, only the written expression can be. The Britannia game is copyrighted, hence no copy can be made that uses the words or pictures in it. However, if someone designed a game about British history from the Roman invasions to the Norman Conquest, and used many or even all of the ideas and techniques of Britannia, but used a different title (which may be trademarked), a different-looking board, and completely rewritten rules, it would be legal, however reprehensible it might otherwise be.
A patent covers a particular expression of an idea. Very few games are covered by patents. The Britannia "game system" has been used in many other published games such as Maharaja (Avalon Hill), Hispania (Azure Wish), and Rus. The fundamental idea for Britannia actually comes from a game called Ancient Conquest, for which I read the rules while watching a game being played. (Recently I bought a used copy of the game, to see what resemblance there is between it and Britannia. It is a hex-based, combat-factor combat table wargame; all the nations have exactly the same number of potential points, and all the nations of one player play at the same time. In other words, there is little resemblance to Brit beyond the fundamental idea, and even that is differently executed.)
I have been aware of this for many, many years, as any experienced game designer is aware, and as has been described numerous times on numerous game designer Web sites and discussion groups. Moreover, I am very careful about my rights (which is why I long ago stopped writing for Dragon Magazine, because they decided to insist in buying all rights to articles, and still do). I would never sell any of my "game systems" to anyone even if I legally could. If anyone tells you that any person or company owns the rights to the "Britannia game system", they simply have no idea what they're talking about--please let me know about it.
(Usual disclaimer: I am not a lawyer, so what I've said is not legal advice. But you can read what the copyright office says.)
Lew Pulsipher, designer, Britannia