Yeah... I had thought that this would be a good way to share messages secretly, but the thing is the moves are nonsensical, so anyone who bothered to check out what the game progresses would know something is up and would google "Chess message encoding" (the fifth result is the blog post for it, lol).

If the moves actually made sense, this would be a lot more useful. There's probably something that can measure how good a move is, so I guess what you can do is make sure that the moves you use to form a message are above a certain threshold. That way, someone looking into the moves wouldn't immediately know that they're being used to encrypt messages. But honestly other than that, I dunno what you can use it for.

What you describe is exactly what the "without blunders" mode attempts to do, but evaluating every possible move for each player to a useful search depth takes a long time, so it doesn't search very far.

Also, the more you restrict the space of allowable moves, the more moves are required to encode a given message.

Oh I didn’t notice that option, cool.

By the way, what was your motivation for creating this?

It's just a fun & interesting idea.

That's what hacking is all about!