I'm making a puzzle game kind of like Cicada 3301, and one step is to inspect my website page with chrome, and look through the html in the source code, an find a hidden code in the form of a comment. I tried to make an html section on the page, then type <!-- ... --> like a normal html comment, but it doesn't work. If you inspect it, it changes some of the characters and acts as code rather than a comment, being in blue rather than green, which would be easier for the player to see.
It may be difficult to hide information in the HTML with GoCentral as the HTML sections cut out a lot of stuff that wouldn't be essential for mainstream use to prevent possible exploits. It may be possible with structured data but I've not tested this use case. https://schema.org/