This one is a variant on broken 159 - broken 135.
The rules are a little complicated, so I'm including the first picture below (courtesy of Andrewsarchus) to show how it works. You can see that entering a digit on one face of the grid determines which single internal 1x1x1 cube is indexed (the
target cell), and that cube has to be indexed by all the other faces, putting a further digit on all the remaining faces. There are three visible faces, the digits on all of which are constrained by their indexing connections to the internal 1x1x1 cubes, but also to any Sudoku constraints we place on the surfaces of these faces (e.g. irregular regions, thermos or other standard Sudoku variants). This can lead to some new and interesting interactions. To solve the puzzle, we need to place digits in all cells of the three visible faces. If the faces are 4x4, we use the digits 1-4, or if they are 6x6 we use the digits 1-6, etc. just like normal Sudoku puzzles.