This post displays some sysudokie snapshots from Nastiest 618, 640 and 651, The bv scan rules, with line marked fish, unique rectangles, Sue de Coq, XYZ-wings, and XY-chains.  A  Sysudoku technique formerly rated extreme gets to stop for a drink.

In Nastiest 618, a 9-wing popped out in line marking. The removal and scattered 9’s prompted me to look at the 9-panel ahead of the bv scan.

I found no other live fish, but did notice the right angle slinks that promise LPO pattern slinks and orphans. This kind of observation on the X-panels I am now accepting early in the Order of Battle. In this case, East to West freeforms show that patterns are limited to one blue and two green. On the main grid, the healthy cluster extends into the bv field to a trap, but since I had bypassed the bv scan, . . .

I came back to find a classic ALS aided Sue de Coq

NWc2=8(1+2)(6+9) ,

sharing one removal with the coloring trap and making an additional removal.

There is also a 425-wing to extend the cluster, but more additionally, . . .

. . . a nice loop to start the collapse.

Longo’s Nastiests continued to make the Sysudoku bv scan look good, as Nastiest 640 falls prey to the classic Sue de Coq Sc4 = 9(3+4)(5+8) ,

then a grouped i891-wing,

and finally, three XY-chain ANL and a nice loop along the XY rails.

The party continues, as Nastiest 651 gifts the bv scan with a regular 169-wing and an extended unique rectangle with an easy removal.

What’s left is almost a BUG, but that makes for quick wrap of blue on a single cluster, without traps. The solution is green.

Next post will review the toughest of the Nastiest Ever review puzzles,

651 + 11 = 662.