Logic Masters Deutschland e.V.

Credit to Jaze for coming up with the Zipper constraint. Thanks also to ViKingPrime for testing this puzzle.

The title is a triple meaning. The first and most tenuous refers to the fact that zips are often a physical constraint of some kind, and unzipping them may allow a person or thing to be set free. The second reassures the solver that this solution path is free of any set theory (apologies for the spoiler, but I doubt this comes as a surprise)!

The third and most relevant is simply an instruction to myself. A few nights ago, I made the ambitious decision to try setting a puzzle from scratch using the Zipper constraint, with which I was very unfamiliar, whilst live on my Twitch channel. I solved a couple of excellent model puzzles by gdc, then opened up a blank grid, after which approximately three hours of frustration and hilariously painful Twitch content ensued. In my defence, I made some interesting logical discoveries, and I think I was quite unlucky that they all ended up breaking, though on reflection there are a number of things I would do differently next time should I attempt a similar challenge.

On my 40-minute cycle to work the following morning, my mind began to hyperfocus on the Zipper line patterns I had tried on stream. Before long I was visualising half a grid's worth of lines and logic, while my sub-conscious did an excellent job of taking the handlebars. I noted these ideas down on my phone during my lunch break, and as if by magic I had the skeleton of a puzzle.

The lesson to learn here is that the creative process is a fickle thing that shies away from cameras but loves the freedom of a nice long cycle ride. I should endeavour to pursue such freedom when setting puzzles in the future, or in other words, my instruction to myself is to set, free.

Play on CTC
Play on f-puzzles



Normal sudoku rules apply.

Digits an equal distance from the center of a lavender 'Zipper Line' must sum to the digit in the middle of that line.