I fell in love with your writing last week and you've still got me in your grip for this round!
Having him be the designer of the Tesseract 19 was an inspired idea!

The many faces of your mind rippling over the dunes.

That would drive anyone mad!

Your ending clinched it for me. All those years without any remorse for the millions of lives he'd been responsible for ending finally getting to him. Again, I loved it!