There is no need to guess, also proves that solution is unique. L stands for left sudoku, R for the right one. (X,Y) means the X is in L, Y in R, the rest should be self-evident. Formatting of sudokus is crappy but I believe it should be clear enough.
L/R, horizontal lines are not drawn.
Solution of L/R at this point is
Now notice that
The name of this puzzle is
I solved the Sudoku, then learned from the other answers here, that the next step is to solve a Yajilin, a puzzle type I haven't heard of before. As these both steps are already covered in the other answers, I only give the combined solution here:
Now the last step is
This is just a work in progress.
The Sudoku looks like this:
That means the colored numbers are:
The surrounding colors looks
I have yet to figure out the significance of those numbers, but I'm working on it.
The colored numbers could be placed like this (according to their relative positions):
The positions of the red and yellow numbers are the only ...
Look at the middle three squares. The unknown numbers are
. . . | 17 23 237 | 13 . .
37 . 12 | . . . | 13 . 27
37 12 . | 178 238 . | . . 27
If you guess any single number in the middle row, that fixes almost everything else in these squares: either
. . . | 1 2 7 | 3 . .
3 . 2 | . . . | 1 . ...