@Arnauld Thanks! I've been lurking here for several months now, so that probably helped. :p

The intro presents the game as having some rule that must be discovered. The reader is then invited to try and find the rule themselves by visiting the TIO link, collapsing the header, and trying inputs themselves - but immediately following this invitation is an explanation of what the rule is, without any indication as such. For me at least I didn't realize that explanation was the "rule" and proceeded to try figuring it out, leading to some confusion and lost time when there seemed to be nothing more to it.

Suggestion: Since you offer to let people play it themselves with the TIO link, consider giving a small warning of some sort before explaining what the solution/rule is. I was a bit confused after reading both paragraphs and then poking in different numbers thinking there would be some additional rule to figure out, only to find that the results were precisely as described.