Puzzle #695 - The Other Backlog (Castle Wall)

Last year before the World Puzzle Championship, I printed off or started a few GMP ebooks to get some practice on a few key genres. One of those was Castle Wall, where I solved about two thirds of the book on the plane ride to Toronto. But that left me with some loose papers of unsolved puzzles that just sat there for ages, as I caught up with and finished the puzz.link database, worked through parts of Toketa 11 that I got at the event, the usual contest routines... until, at the time of this posting, about a month and a half ago. I finally just sat down and started finishing these ebooks, and in doing so I obviously did Serkan's giant Castle Wall at the end of the book. There was one particular section that I kept wanting to make a particular deduction that was very close to working, and ultimately was never used in the solve. So naturally, I made a puzzle using that deduction.

puzz.link interface

Now I just need to find progress on the last 4 pencil Tapa LITS in Toketa....