luftmensch - I agree there's an ambiguity about the first cell of 31d. Perhaps the trick is not to draw a vertical line on either side of it but rather to let the 3rd and 4th letters merge into each other, as they do in the original. I was more bothered about how to reconcile drawing the neither horizontal nor vertical lines around or through the decidedly sqaure squares in the grid's north-east section.
Tough but fair, and a brilliant construction! I much prefer this type of puzzle where the theme, instructions, and “end” game appear gradually and feed back into each other. Last week’s was closer to all-or-nothing and rather gruelling!
Just to add my voice to the chorus of admiration and thanks to Cranberry. Thoroughly enjoyed both the gridfill and the endgame; great construction and very apt for the date.
Late to the puzzle, but have just passed a delightful three hours with it. Tough but eminently fair and, as some have noted, a stunning logistical effort. Many thanks to Cranberry👌