Puzzles #391 - 400 - MadMahogany's Christmas Tree Conundrum (Shading and Sudoku Medley)

Like the last two years, I took part in the Secret Solver event on Puzzlers Club. This time around, I got MadMahogany, someone I mostly know is semi-active (I think?) on the CTC Discord, and some of their most memorable puzzles they've posted to their blog have been shading or sudoku puzzles. Sudoku is obviously outside my general comfort zone, but whatever, this was the perfect opportunity to go big and make something incredible. So I made a Samurai Sudoku shaped like a Christmas tree with different variants in each subgrid. Rules after the puzzle images.

penpa interface

Nurikabe | Tasquare | Canal View | Nuribou | Nurimisaki | Kurotto | Mochikoro | Cave | Kurodoko

I also decided to make a collection of 5x5 shading puzzles themed on 12/25 (as close as I could get it) for each shading puzzle variant in the big puzzle. Rules for Nurikabe, Tasquare, Canal View, Nuribou, Kurotto, Kurodoko, Nurimisaki, Mochikoro and Cave can be found linked here, as well as Sudoku. These 9 puzzles were a last minute addition when I finished with time to spare, and I thought it would be nice to have a brief reminder / demonstration of the shading rules before having to dig into the tree itself.

"penpa" link (the URL is too long for some browsers, so go to Penpa, select "Load" from the top bar, and paste the URL from the pastebin into that box to load the puzzle)

So, here's the tree. Standard rules apply for each puzzle type within each labelled subgrid. Some grids overlap: the contents must satisfy all rules from both grids when taken only for that grid. As an example, Kurodoko requires shaded cells to not be adjacent to other shaded cells. This rule only applies within the Kurodoko grid, and so a shaded cell on the edge could be adjacent to a shaded cell in another grid. Any cell with an outlined gray circle will have its value act as a clue for the shading puzzle in that grid. Note that most thermos and arrows have the circles coincide with shading clues, but not all. A rundown of each variant rule follows. Star Battle - 1s and 2s may not share an edge or corner with each other. Thermo - numbers must strictly increase from the circle to the end. Arrow - the sum of all numbers on the arrow must equal the number in the circle. Classic - no additional restrictions apply. XV - Cells separated by a V must sum to 5. Cells separated by an X must sum to 10. Cells separated by an XV must sum to 15. Not all Xs or Vs are given. Kropki - Cells separated by a white dot must differ by exactly 1. Cells separated by a black dot must have one number be exactly double the other number. Not all dots are given. Difference - Cells separated by a red dot must have a difference of the number inside the dot. Killer - Cells inside a cage must sum to the value in the cage, and must not repeat within a cage. Product - Cells separated by a pentagon must have a product of the number inside the pentagon.

This puzzle took me probably 30 hours across several weeks to construct, and I got to work with a couple rulesets I'd never worked with before. Like overlapping grids (somehow this was new to me- many headaches from contradictions across grids though...), most of these number placement variants (Arrows are a huge pain, and Killer is way harder than I thought it would be), and Mochikoro and Canal View (fun and easy, painful and difficult. Though some of the Canal View pain was from the other restrictions, it's hard to make unique!). Special mention goes to the Nurikabe for being an absolutely massive gigantic pain to make unique, and the Cave, and the Kurotto section, and generally huge parts of this puzzle barely work. But it all comes together beautifully and I'm very proud of what I came up with here. And my solver liked it, too. :)

I'd also like to take this space to thank Rever for testsolving most of this puzzle before I sent it out, Swaroop for updating Penpa to even support grids this big, and djmathman for making the gift I received, which is really quite excellent.

That's all for now, sorry about the inactivity here, more puzzles soon once I write up the posts for them because I have another 8 waiting already. Errata: added a white kropki dot I thought was unnecessary, but was made necessary due to a bad deduction in completely different section.