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)

Theme: GM Puzzles

Rules: Standard Statue Park rules.

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

Time Standards (highlight to view): Grandmaster = 4:00, Master = 6:00, Expert = 12:00

Solution: PDF

Note: Follow this link for other Statue Park Puzzles. If you are new to this puzzle type, here are our easiest Statue Parks to get started on.

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

(View image directly for larger form.)

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the composite Yajilin mode where left click marks cells, right click marks dots in cells or X’s on edges, left click+drag draws lines.)

Theme: Logical

Rules: Standard Tapa rules.

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

Time Standards (highlight to view): Grandmaster = 8:30, Master = 14:00, Expert = 28:00

Solution: PDF

PDF

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

Theme: Tire Tracks

Rules: Standard Star Battle rules. Two stars per row, column, and region.

Answer String: For each row from top to bottom, enter the number of the first column from the left where a star appears. Enter these numbers as a single string with no separators.

Time Standards (highlight to view): Grandmaster = 1:15, Master = 1:45, Expert = 3:30

Solution: PDF

Note: Follow this link for other classic Star Battles and this link for Star Battle variations. If you are new to this puzzle type, here are our easiest Star Battles to get started on. More Star Battle puzzles can be found in The Art of Puzzles, in the book Star Battle by JinHoo Ahn, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

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.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the composite Yajilin mode where left click marks cells, right click marks dots in cells or X’s on edges, left click+drag draws lines.)

Theme: Logical

Rules: Standard Tapa rules.

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

Time Standards (highlight to view): Grandmaster = 5:00, Master = 7:45, Expert = 15:30

Solution: PDF

View image directly for a larger form.

PDF

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

Theme: Logic

Rules: Standard Yajilin rules.

Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. If the loop only has vertical segments in the marked row, enter 0. Separate each row’s entry with a comma.

Time Standards (highlight to view): Grandmaster = 12:00, Master = 22:30, Expert = 45:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between edgex mode where left click+drag draws lines and right click marks X’s and a shading mode to mark true/false clues.)

This is a “Franken-Friday” puzzle variation.

Theme: Logical

Rules: Variation of standard Slitherlink rules. Exactly one clue in each row and column is lying and must represent a different number.

Answer String: Enter the length in cells of each of the internal loop 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 = 6:45, Master = 12:00, Expert = 24:00

Solution: PDF