## Puzzle #61: Dynasty Quartet

### Genres: Heyawake, Yajisan-Kazusan, Star Battle, Kurodoko

This is a hybrid dynasty puzzle, made as part of a Secret Santa event for Teal.

Each quadrant is a puzzle of the dynasty (named for Smullyanic Dynasty) variety, with the standard rules for that genre. As well, for each coordinate in each puzzle (i.e. every Row 4, Column 6), exactly one of the puzzles has a shaded cell, with the exception of the one cell for which all four cells are marked with a cross, which should remain unshaded in all four grids.

Dots are only for location purposes.

Detailed genre rules:

- In all four genres:
- No two shaded cells may be orthogonally adjacent
- The unshaded cells must form a single orthogonally connected area.

- Heyawake:
- Numbered regions must contain the indicated amount of shaded cells.
- A line of consecutive unshaded cells may not cross more than one bold border.

- Yajisan-Kazusan:
- If a cell with a number in it is unshaded, the number represents how many shaded cells are in a straight line in the indicated direction.
- If a cell with a number in it is shaded, the number is meaningless, and its clue may be satisfied or unsatisfied.

- Star Battle but shading:
- Exactly two cells should be shaded in each row, column, and region. No two shaded cells may be adjacent diagonally.

- Kurodoko:
- Clues cannot be shaded, and represent the total number of unshaded cells that can be seen in a straight line vertically or horizontally, including itself.

Also, I should warn you: this is a very difficult puzzle, and I’d recommend you learn river theory; unfortunately, the only resources I know on the theory that are publicly available are these two blog posts, written in Japanese, a language I do not speak. (If anyone wants to post an explanation of river theory in English somewhere I can link it, please send it to me either through email at `[first part of this site's domain name] [commercial at] [rest of the domain name]`

or through any other method you already know me from.)

And finally, massive thanks to IHNN for test-solving this puzzle, and to athin for my own gift.