IcoSoku

Some time ago I was presented with this game (for 1 person). I must admit that I think it quite difficult. Mostly trial and error for me. Although my first play with it was immediately successful.

So, how does this work? The 12 yellow pins and the 20 white triangles are all removed. Then the yellow pins are placed in the holes for the pins, but randomly. The pins are numbered 1 to 12.
In the next step all triangles need to be placed too. These triangles have black spots in every corner, something between 0 and 3. The goal is to place them in such a way in the puzzle that the sum of black dots around a yellow pin is the same as the number on that pin.

I believe there are approximately 4 million different possibilities, and according to the vendor every single one of them is solvable.