Please note that how many hitpoints a character has or how much damage a sword does is not a violation of copyright. Please note that Title 17 of the United States Code states:

• In section 102 (b) "In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work."

Furthermore, the following bulleted items are a few statements issued by the U.S. Copyright Office:

• Games
  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.
• Copyright does not protect ideas, concepts, systems, or methods of doing something. You may express your ideas in writing or drawings and claim copyright in your description, but be aware that copyright will not protect the idea itself as revealed in your written or artistic work.
• Copyright does not protect facts, ideas, systems, or methods of operation, although it may protect the way these things are expressed.
• WHAT IS NOT PROTECTED BY COPYRIGHT?
  Several categories of material are generally not eligible for federal copyright protection. These include among others:
  Ideas, procedures, methods, systems, processes, concepts, principles, discoveries, or devices, as distinguished from a description, explanation, or illustration
• EXTENT OF COPYRIGHT PROTECTION
  Copyright protection extends to all of the copyrightable expression embodied in the computer program. Copyright protection is not available for ideas, program logic, algorithms, systems, methods, concepts, or layouts.

But couldn't the game rules be patented? Let's look at what can be patented.

• 35 U.S.C. 101 Inventions patentable.
  Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.
• The United States Patent and Trademark Office (USPTO) in its General Information Concerning Patents brochure offers the following guide to what that means:
  "The word “process” is defined by law as a process, act or method, and primarily includes industrial or technical processes. The term “machine” used in the statute needs no explanation. The term “manufacture” refers to articles that are made, and includes all manufactured articles. The term “composition of matter” relates to chemical compositions and may include mixtures of ingredients as well as new chemical compounds. These classes of subject matter taken together include practically everything that is made by man and the processes for making the products."

As good as defining the word "process" as meaning "a process" is, let's get a little clearer definition of what it means. The following is taken from Black's Law Dictionary 9th Edition:

It would appear that the publication of the game rules/mechanics would not encroach or threaten a company's legal rights.

As always, please consult with a licensed attorney before proceeding in any questionable activity or legal matter. The information expressed here is not legal advice and should not be taken as such. For further information please visit the official website of the U.S. Copyright Office.