True.
Ideas are not subject to copyright protection; only the expression of the ideas.
Ideas cannot be protected by copyright, only the expression of the ideas.
Ideas cannot be protected; only the expression of those ideas.
Ideas cannot be protected by copyright: only the expression of the ideas.
Ideas cannot be protected by copyright; only the expression of the ideas.
Ideas cannot be protected by copyright, only the original expression of those ideas, fixed in a tangible form, can be.
Ideas cannot be protected; only the expression of them.
Ideas cannot be protected by copyright, but the expression of them can be. A script, for example, is copyrightable.
Backgammon itself, as a game, cannot be copyrighted because copyright protects original expressions of ideas rather than the ideas or rules themselves. However, specific artistic elements related to the game, such as its board design, unique artwork, or instructional materials, can be copyrighted. Additionally, trademark protection may apply to specific names or branding associated with the game.
No ideas are not necessarily under copyright law. If you publish it on the web, a book, and/or record it, the copyright is yours but the "idea, procedure, process, system, method of operation, concept, principle, or discovery" you have described is free of any copyright. Some ideas can be protected to the limited extent that they are implemented in a patented invention. Other ideas are protected merely by keeping them secret.
Copyright does not protect ideas, only the expression of those ideas.
Ideas cannot be protected by copyright; only the expression of those ideas. If you write a script, it is automatically protected; registration is not required.