Though I like this a lot, as has been said, there are some obvious ways to crack it. There would be ways around this though, so as a proof of concept for one specific site it is pretty cool.
In order to contribute to the ways in which this can be 'broken', I present you with a brute force, not on the server, but on the chess game itself:
http://bookmarkify.it/114
(this is a bookmarklet, but you can also just copy-paste the code from the editor (scroll down) and paste it in your console).
In order to contribute to the ways in which this can be 'broken', I present you with a brute force, not on the server, but on the chess game itself:
http://bookmarkify.it/114 (this is a bookmarklet, but you can also just copy-paste the code from the editor (scroll down) and paste it in your console).