I came across this door on the west coast, and I thought I already understood all these puzzle elements, but I don’t see any way it can be solved.

My understanding of the rules involved here are:

1. I must make the shapes for the yellow blocks. The one on the far right is rotatable, but the other is not.

2. The blue blocks subtract from the yellow blocks.

3. My path must go through every single black dot (so, in this case, every single intersection on the board).I’m interested in the solution, obviously, but more so I’m interested in if I’m missing or misunderstanding some of the rules here.

**Answer**

There’s a possible interaction between your numbers 1 and 2 that you’re missing. The blue blocks only subtract from yellow blocks that are in the same space. Let’s work with an example 2 box puzzle. If there’s one blue block in one box, and a yellow block in the other, the solution is to go around the edge of the puzzle, not to go through the middle, splitting them up. If you cordon off the blue block from the yellow block, then the blue block doesn’t do its thing, so it’s not a valid puzzle solution.

So, be sure that you design a solution that has all the blue blocks in the same space as yellow blocks.

And yes, this is a super tough puzzle, it took me quite a bit of fiddling to get everything in place.

As you requested in the comments, here’s a quick solution. Took me less time this time around, since I vaguely recalled some of the tricks I used in the solution.

**Attribution***Source : Link , Question Author : Sterno , Answer Author : Keen*