Logic Masters Deutschland e.V.

So good they named it twice, eh? See, while it was Klomp who introduced the concept of 5 being a "shy digit", it was Old Miles's use of it in this XV sudoku that inspired me to have my own tussle with the ruleset. In that puzzle, the 5s were considered to be "courteous", which is the name I gave to the concept in my initial WIPs solely because of the hard-C alliteration, but then in the comments SudokuExplorer suggested thinking of them as chameleons and I've gotta say I like that rather more. It explains why they take the box number to fit in as opposed to something dependent on their neighbours: they camouflage to match their background, which is the box they're in. Admittedly this is based on the mythos of the chameleon as opposed to its actual colour-changing abilities, which I think are mostly limited to social signals and environmental responses, but still... hard-C alliteration! I'm not in the position to make authoritative declarations as to what this rule should be called by any stretch of the imagination, hence the compromise title. If you really, really want to, you can pretend that the chameleons themselves are shy...

The power of the negative constraint was a bit of a hassle to work with, so the logic in the puzzle's kinda front-loaded; there are three little set-pieces I think you need/ought to work through before you can start dancing around the grid with abandon, and I'm happy with them at least. As always, I wish folks the best of luck, but here I do really mean it because although the logic in this puzzle isn't particularly difficult, its ruleset will occasionally attempt to twist your brain into some interesting shapes. Yes, 5 is sometimes half of 6, and sometimes it's consecutive with 8. That's just the way the cookie crumbles. Comments and complaints are welcome, and I hope you enjoy the puzzle!

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Rules
Normal Sudoku rules apply.
"Kropki" rules apply: white dots separate cells whose values are consecutive, while black dots separate cells whose values have a ratio of 1:2. All such dots have been given, so the negative constraint applies.
For the purposes of evaluating the Kropki rules, the 5s in the grid act like chameleons, camouflaging themselves against the background of their box. To that end, the "value" of cells that contain a 5 is considered to be their box number. For example, if the 5 in box 2 were adjacent to a 3, there would have to be a white dot between them, since the 5 would act like a 2 and thus be consecutive with the 3. Similarly, a black dot would have to appear between the 5 and a 4, as opposed to the typical white dot!

Here's a link to the grid set out in f-puzzles - note that the Kropki dots are purely cosmetic, and the particulars of the rules mean that checking and conflict highlighting are limited solely to normal sudoku, so you may wish to tread carefully...

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Since the chameleon behaviour isn't the most straightforward thing to wrap your head around, especially when you consider how it acts across box boundaries, here's a little example diagram, showing a valid configuration over boxes 1, 2 & 4:

:

Three things to note: firstly, adjacent cells whose values are 1 and 2 can be separated by either a white or a black dot, as seen above with R3C3. Secondly, you can have adjacent cells with the same value, as demonstrated here with R4C1 & R4C2 - hence the slightly clunky "value" wording in the ruleset. Thirdly, the negative constraint applies to the 5s just as much as it does to the other digits; if any of the dots above were removed, then the example arrangement would be rendered invalid!