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: Clue Symmetry and Logic

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 marked column, enter the length in cells of the longest vertical segment. Enter 0 if there are no vertical segments. Enter these values as a single string (eg “230124”).

Time Standards (highlight to view): Grandmaster = 4:15, Master = 7:30, Expert = 15:00

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.)

Theme: Clue Symmetry and Logic

Rules: Locate some blocks in the grid, either 1×2 or 1×3 in size, with each block containing one of the given numbers. Each block is allowed to move in its long direction, stopped only by an edge of the grid or another block. A block’s number must indicate the total possible movement of the block. Or see here.

Answer String: Enter the size of consecutive groups of cells that belong to blocks in each marked row from left to right, separating each row’s entry with a comma (ie “151,22,44,22”).

Time Standards (highlight to view): Grandmaster = 3:15, Master = 5:30, Expert = 11:00

Solution: PDF

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: “Easy” Practice (this was a WPC puzzle style)

Rules: Place each of the 11 pentominoes into the grid exactly once, with rotations and reflections allowed, to form a valid “Coral”. In a Coral puzzle, all blackened areas are connected, but no group of 2×2 cells is entirely blackened. Also, there are no unshaded areas enclosed by the coral (meaning each unshaded cell must have a path through its edges with other unshaded cells to a border). Numbers outside the grid indicate the lengths of groups of shaded cells in that row/column, but not necessarily in order.

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

Answer String: Enter the identities of the pentominoes (one capital letter for each, even if in multiple cells) appearing in the marked rows from left to right (eg “ILN,WVXT”).

Time Standards (highlight to view): Grandmaster = 4:15, Master = 6:30, Expert = 13:00

Solution: PDF

Editorial Note: Many solvers can confuse Coral with another puzzle type with similar spelling. An easy way to remember the difference is that Cave has no R’s and also has no 2×2 Region constraint. Coral puzzles, with an R, do have this region constraint. The other general rules (about not enclosing white spaces and having a single shaded group) are shared between Cave and Coral puzzles.

(View image directly for larger form.)

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

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.

(View image directly for larger form.)

(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