crackingthecryptic

Castle Wall Yin Yang #1 by Magnus Josefsson

Added 2023-01-02 23:49:40 +0000 UTC

Here is a brand new puzzle type invented by the brilliant setter/solver Magnus Josefsson. It's got a fairly intricate ruleset, which is why we were a little worried about attempting it on the channel. However, if you're prepared to work on the rules, it's an absolutely fantastic puzzle. The link to Simon attempting the puzzle in a bonus video is below but do have a go at it first if you can.

Play it at the link below:

https://app.crackingthecryptic.com/sudoku/6DPBrnQGLp

There is also an example puzzle here (as well as a second more complicated puzzle with the same rules!):

https://logic-masters.de/Raetselportal/Raetsel/zeigen.php?id=000CBD

Rules: Shade some cells in the grid so that: All shaded cells are orthogonally connected; all unshaded cells are orthogonally connected; and no 2x2 area is entirely shaded or entirely unshaded. Also draw a single closed loop through the grid such that: the loop must pass through all of the shaded cells along its path consecutively (In other words, it may only visit the shaded and unshaded regions once each); all shaded clue cells must be fully outside the loop; all unshaded clue cells must be fully inside the loop; if a clue cell contains a value it indicates the number of times the loop crosses a cell border in the given direction. The central 2x2 area is not part of the grid and is left empty.

Simon's attempt:

https://youtu.be/IVbNOQaVhwM