Broken Sign Blog
#082: Rail Pool (Forgetful) — "Sudoku"
19 February 2023I participated in a speedsetting competition on the Cracking the Cryptic Discord server for the first time. The goal was to construct a Sudoku-themed puzzle that isn’t a Sudoku within an hour(ish). This puzzle ended up making second place!
Unfortunately, I only found out the event was happening about 10 minutes before the deadline, but thankfully that deadline got extended by 15 minutes. I somehow managed to construct and test solve this in about 15 minutes total.
A Sudoku-themed Rail Pool was actually one of the very first things I tried in the genre. It took me way too long to realise that I was constructing a full loop on an odd-sized grid, and ended up patching it with an unused cell. Now that the Forgetful variant is a thing, I thought this contest was a great opportunity to revisit the theme in a much cleaner way and finally construct an easier Forgetful Rail Pool to publish afterwards.
And just to clarify, this is not a valid Sudoku, it’s just meant to look like one.
Rules: Draw a non-intersecting loop through the centres of all cells. Some boldly outlined regions contain number clues. If a straight loop segment visits any cells of a clued region, its length must match one of these numbers. Each number must correspond to at least one such loop segment. Question marks represent any positive integer, but numbers cannot repeat within a region.
Variant: Forgetful — The loop omits exactly one cell in each region.