This post highlights David Badger’s two advance puzzles in the Sudoku 1001 Hard Puzzles sysudokie review, both starting with the almost nice loops to be found along the XY railway.
In 301, the black XY ANL removes two 7’s, and the red extension ANL, two more.
The extra bv allow the XY railway to expand. Coloring extends along a (red) spur in the North box.
The cluster traps 4’s in N and C boxes, and the extension coloring wraps green, confirming blue for the collapse.
Turning to 101, there’s a weak bypass, and relatively difficult box and line markings, with columns heavily favored over rows.
An indecisive ALS/XZ turns up in the bv scan, but I found nothing else.
On the X-panels, a 4-chain organized the 4’s of the North bank by box/line interaction.
The removal of 4r2c6 enables a 361-wing with an i-wink victim. It sees the third 1 of the wing by forcing chain.
Plenty of bv for coloring. But the slinks are divided among three clusters. Fortunately in the red/orange cluster, 5r7c5 is found guilty of generating two more 16 bv in the Center box, to go along with the one already in place. The 5r7c5 removal would be decisive in itself, but with the coloring it wraps orange, which, as shown by the arrows, confirms green and violet.
The bottom line on David Badger’s huge collection, his foray into “ordinary Sudoku”, is a constantly entertaining basic level, and a challenging advanced level, if you have the patience to get there.
You never know what the next puzzle is going to be. Kinda’ like the Arabian 1001 nights.
Next time, I jump ahead of myself to preview a review, by taking on Manuel Castillo’s Only Extreme 3. It’s an opportunity to say one more thing about the AIC slink. You may find a way to skirt the trials featured in this post.