I added a link to Andernach Chess. Since you were styling your headings instead of using h? tags, I replaced your <strong> tags with <h3> and your <u> tags with <h4>. It is unclear whether progression is a standard part of the game or you are also describing a progressive chess variant of your game. Since some games do have progressive chess variants, you should make it clear whether or not that is what you are doing.
I added a link to Andernach Chess. Since you were styling your headings instead of using h? tags, I replaced your
<strong>tags with<h3>and your<u>tags with<h4>. It is unclear whether progression is a standard part of the game or you are also describing a progressive chess variant of your game. Since some games do have progressive chess variants, you should make it clear whether or not that is what you are doing.