"The Mad Gnome and the Earthquake Machine" by David Dolph
One thing I love about this OPD, aside from the puzzles and tile clues to help at the very end, is the premise itself. I really dig the idea of an insane architect whose creations were secretly death traps that would reveal their horrible nature over time. Dolph did a great job creating a villain we can love to hate, but do nothing about it directly to him, aside from foil his final revenge plot. From a few lines of text, I was able to flesh this NPC out almost instantly. I imagined him creating the switches to deactivate the earthquake machine not only as a means to exact revenge after his demise, but also as a way to feel like the most powerful figure the city while he was alive, able to save or destroy the citizens on a whim.