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PDF

or solve online (using our beta test of Penpa-Edit tools; use Tab to alternate between number entry and shading)

Theme: String Lengths

Rules: Variation of Nurikabe and Scrabble/Criss-Cross puzzles.

Place the 12 number strings into the grid, reading from left to right or from top to bottom, so they are all connected criss-cross style and also form a valid Nurikabe ocean. No unlisted string can appear anywhere, not even two-character ones, and the strings do not occupy any 2×2 area. The remaining white cells are part of islands as in a Nurikabe puzzle. Each island is represented by one number in the grid which equals its size in cells.

Or see this example from the 22nd WPC instruction booklet.

Answer String: For each column from left to right, enter the total count of zeroes from the entered strings. Enter the result as a single string (eg “401120…”)

Time Standards (highlight to view): Grandmaster = 7:00, Master = 15:00, Expert = 30:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools using a composite mode where left click inside cell shades square, left click + drag draws line segment, right click inside cell adds dot, and right click on cell edge adds an x; an additional shading mode is available by hitting the tab button if that is preferred.)

Theme: Hidden

Rules: Blacken some cells and then draw a single non-intersecting loop through all remaining white cells. Outside clues indicate the size of all groups of blackened cells in that row or column in order. There must be at least one white cell between each of these groups. When no clues are given, any number of cells may be shaded in that row/column. Or see here.

Answer String: For each column from left to right, enter the number of turns the loop makes. Enter your result as a single string (eg “202204…”).

Time Standards (highlight to view): Grandmaster = 1:45, Master = 2:30, Expert = 5:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: 22nd WPC in 2013 (the shaded box is just meant to accentuate the theme and has no role in solving). This puzzle type appeared in Round 7 of the WPC from the Serbian constructors under the name “False Doppelblock”

Rules: Fill each row and column of the grid with the numbers 1-6 and two blackened cells. In this false variation, clue numbers outside the grid are either one higher or one lower than the sum of the digits between the two blackened cells in that row/column. True sums can equal zero if the black cells touch. Or see here, but remember this puzzle is a “false” variation with +1/-1 clues unlike that example.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 8th row from left to right. Use an X (capital letter) for each blackened square.

Time Standards (highlight to view): Grandmaster = 10:00, Master = 17:30, Expert = 35:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: Logic/New Variation

Rules: Standard TomTom rules, using digits from 1-6. Also, consecutive digits (for example, 2 and 3) are not allowed to share an edge inside a bold cage. Consecutive digits are allowed to touch along the bold borders that separate cages.

See also this example:

Answer String: Enter the 2nd row from left to right, followed by a comma, followed by the 2nd column from top to bottom.

Time Standards (highlight to view): Grandmaster = 2:15, Master = 3:15, Expert = 6:30

Solution: PDF

Note: Follow this link for other classic TomTom. If you are new to this puzzle type, here are our easiest TomTom to get started on.

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: Surprise Sudoku

Rules: Standard Sudoku rules. Also, there is a mystery rule that must be determined by looking at the example at the top of the puzzle.

Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 9th row from left to right.

Time Standards (highlight to view): Grandmaster = 6:15, Master = 8:30, Expert = 17:00

Solution: PDF

Editorial Note: While this is an original sudoku for GM Puzzles, this particular “surprise” gimmick from Serkan first appeared on the SudokuCup 10 test with a different puzzle.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the linex mode where left click+drag draws lines and right click marks X’s)

Theme: Dominoes — in both the clues and the variation rules

Rules: Standard Cave rules. Also, the exterior of the cave (the cells not seen by the numbers) must be divisible into dominoes (1×2 rectangles) in at least one way.

Answer String: Enter the length in cells of each of the cave segments from left to right for the marked rows, starting at the top. Separate each row’s entry with a comma.

Time Standards (highlight to view): Grandmaster = 4:15, Master = 9:00, Expert = 18:00

Solution: PDF and solving animation.

Note: Follow this link for other classic Caves. If you are new to this puzzle type, here are our easiest Cave Puzzles to get started on.

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(PNG with extra lines for solvers who want to flood-fill the path)

or solve online (using our beta test of Penpa-Edit tools using a composite mode where left click inside cell shades square, left click + drag draws line segment, right click inside cell adds dot, and right click on cell edge adds an x.)

PDF

Theme: T

Rules: Find a path from one dot to the other by moving horizontally or vertically between adjacent squares. The path cannot touch itself, even diagonally. All highlighted regions must be used, and may be re-entered. If two or more highlighted regions have the same shape and orientation, then how the path passes through those shapes must be identical. Or see here.

Answer String: For each marked row, enter the size of each group of cells used by the path from left to right. Separate each row’s entry with a comma.

Time Standards (highlight to view): Grandmaster = 2:45, Master = 5:30, Expert = 11:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools)

Theme: Clue Symmetry and Logic

Rules: Variation of Skyscrapers rules. Place digits 1-6 into the grid so that no digit is repeated within a row or column. Digits outside the grid indicate the number of buildings that can be seen from the corresponding direction. The buildings form two-digit numbers and the relations between some numbers are shown with a greater than/less than sign.

Or, see here.

Answer String: Enter the 3rd row from left to right, followed by a comma, followed by the 4th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 5:15, Master = 7:30, Expert = 15:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: Trapped in A box

Rules: Either shade or add a single letter (A, B, or C) to each square so that each row and column contains exactly one A, one B, one C, and the rest shaded squares. Cells in the grid already marked with a letter can be shaded or remain unchanged.

Letters outside the grid indicate the first letter seen from that direction.

Numbers outside the grid describe the size of groups of consecutive shaded squares in that row or column in order. There must be at least one unshaded square between groups.

Or, see here.

Answer String: Enter the number of the column where the B is placed in each row, starting with the top row and proceeding to the bottom.

Time Standards (highlight to view): Grandmaster = 4:30, Master = 5:45, Expert = 11:30

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools in edgex mode where left click+drag draws lines and right click marks X’s)

Theme: Unfriendly Neighbors

Rules: Standard Slitherlink rules. Also, there are some sheep (marked S) that must be inside the loop and some wolves (marked W) that must be outside the loop.

Answer String: Enter the length in cells of each of the internal loop segments following the arrows for the marked rows, starting at the top. Separate each row’s entry with a comma.

Time Standards (highlight to view): Grandmaster = 2:15, Master = 3:00, Expert = 6:00

Solution: PDF