Game rules are not subject to copyright. Game rules cannot be patented, although in certain jurisdictions, game mechanics can be patented. An example of a mechanic is the Magic the Gathering "tap" mechanic, which is one of the most well known game mechanics subject to a patent in the United States. Even if patented, it's the use or application of the patented mechanic that is contrary to the owner's rights, not the publication thereof. In fact, to obtain a patent, the owner has to make the mechanic publicly available in the patent registry. Canada specifically forbids patents based on board games, although the US and UK allow limited patenting in the case of novel mechanics following the standard tests for originality and non-obviousness.
US:
http://www.copyright.gov/fls/fl108.html
Canada:
http://www.cipo.ic.gc.ca/eic/site/cipoin...l#whatcant
UK:
http://www.ipo.gov.uk/types/copy/c-applies.htm
An interesting article from games designer's point of view:
http://www.gamesdiner.com/2009/08/game-r...ted-by-law
GW can send threatening letters all they want, but they aren't backed by anything. The fact that forums/individuals cave in means nothing except those individuals don't understand the law or don't have a spine to stand up for themselves.
Points costs, unit stats, and rules descriptions are all fair game. GW doesn't own any interest in any of those. What they have is a protection of their specific expression as published in their literary works.
And although I am not providing legal advice, in any way, I am a lawyer and very familiar with copyright and intellectual property issues.
I am fully within my rights to say the following:
A Leman Russ Battle Tank in the Imperial Guard Codex costs 150 points, has Armour Value 14 on the front, Armour Value 13 on the sides, Armour value 10 on the rear. It comes equipped with a Battle Cannon on the turret, as well as a hull mounted Heavy Bolter. It has a searchlight as well as smoke launchers standard. It has a number of options including... bla bla bla sponsons... equip, etc. You get the idea.
GW has never made the above specific expression, so they can't prohibit its publication.
Their C&D letters are a scare tactic. That said, they may file a nuisance law suit, and you probably wouldn't be able to afford to fight it properly, even if it is totally without merit.
Someday, I'd like to see someone, somewhere, stand up to them. Too many forums and other sites just immediately comply with their frivolous demands, which actually infringes on our consumer rights.