I liked the four towers idea and can't wait to play your next tower dungeon. For some reason I really liked the Run and Run part. Maybe could have used an imaginary wall though.
I have to agree that finding the key down a pit was a real job. I didn't like that some monsters were not capable of fighting, i.e. some spiders on top level of the towers were trapped on preasure pads. Demons or Poison Slimes would have worked there quite well I imagine.
Good job and great dungeon! I look forward to playing your others.