LPB 48, the first review puzzle of Lucky Panda Books 504 Sudoku Puzzles, features an interesting hidden dublex and many unresolved 3-fills with fill strings trimmed by line slinks. The easy line marking closes with a DIY unique rectangle. A large bv field enables a coloring finish, with or without an XY ANL and a follow up UR.

It’s easy to dismiss the this large size paperback, especially when you see the back cover, and the two pages of explanations, basic tips and techniques. The collection is nothing like “Extremely Hard”, or “Insanely Difficult”, as claimed , and working all 504 will not bring you to a state of peak Sudoku mastery. Review puzzles 48, 96, . . . 480 are entertaining at the basic and early Advanced levels, and have instructive moments.

The layout is different: four puzzles to a page and answers to the eight puzzles of a spread at the bottom of the next spread. The review puzzles are on the bottom right corner of every sixth spread.

The Basic trace of  LPB 48 is promising. A host of 3-fills, many unresolved, stretch the bypass trace across the page, to a hidden dublex on value 9? And a breakout in the line marking close.

The bypassed grid reveals the story of the hidden dublex.

Taking out the SE9, you see that the S9 is confined to rows r78, a double line exclusion forcing SE9 into r9, while N9 keeps NE9 in c8.

Want to be a master of Sysudoku Basic?

Read traces.

Now a look at the Line marked grid, to pick up on something I just realized about 3-fills and line marking. In box marking, you can shorten the 3-fill strings by removing any value closed in the line.  Note how row fill strings of 3-fills are shortened by this action.

Also, Advance overlaps Basic with a variation of UR Type 1, as 4r5c4 removes both 4 and 6 from r78c4.

Both XY chains and coloring are favored by the bv forest. Coloring goes all the way from here, but an interesting side trail is XY ANL, with follow up

that removes 4’s and enables

another unique rectangle, Type 1.

Coloring resolves the near BUG and wraps blue for the collapse of LuckyPanda 48.

Next in the review, LuckyPanda 96 to the right,  is a bypass casualty.

The bypass trace will be here next week, with a solution of number 3, Lucky Panda 144 at the left.