Warning: this post contains a WarTron spoiler. Actually, it's even worse than that, because this post will spoil the surprise of a puzzle but won't even give you the answer. What this is... This is a puzzle idea I couldn't get out of my head. Remember the coasters puzzle? I failed to help my team at all with the coasters puzzle. That's because I got a puzzle idea lodged in my brain and couldn't get it out. This idea obviously didn't lead to anything promising, but I kept going back to it, thinking about it.
Even now as I try to work on a WarTron write-up, thoughts of this other puzzle idea stick in my brain. (Yes, my progress on the writeup has only made it about 15 minutes into the pre-game activity. Look, I have a very deliberate process that I need to follow here and... Uhm, sorry, what was the question?) Was it a workable idea? Or was it too constrained, impossible to make a message from? So I had to sit down and try to make a puzzle. Right? That's the only way to know, right?
Suppose that the coasters didn't have a cool "frame". Just images, blanks, and mysterious "M x . , N x -" text? Oh yeah, and what if the words weren't all four letters long? What then, hotshot?
There, now my puzzle idea is forever lodged in your brain, too. My work here is done.