Since maps only works in iframes and I my browsers don’t like that. After a dozen attempts to brute force, I considered it fair to put a breakpoint in js and look at the stack (a habit I gained after playing untrusted ). I only glimpsed at the code for what was still ahead. When I encountered the chess question I decided to go finally to bed - since that wasn’t the last rule or even close. I guess Friday after work would be the best time to start this again.