PDF

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

Theme: X’s and O’s (for Jamie Hargrove)

Author/Opus: This is the 291st puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Shade some cells black so that all unshaded number and arrow clues indicate the exact count of shaded cells in the given direction. Shaded cells cannot share an edge, and all white cells must remain connected as part of a single contiguous group. It is allowed to shade over some of the numbered cells; a shaded over clue may or may not be true.

Also, see this example:

Answer String: For each row from top to bottom, enter the number of shaded cells as a single string. For the example, the answer is “20212”.

Time Standards (highlight to view): Grandmaster = 2:30, Master = 4:30, Expert = 9:00

Solution: PDF

Note: Follow this link for other less common Shading puzzles.

(view directly for a larger image)

PDF

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

Theme: GMP (see Bridge Shapes)

Author/Opus: This is the 1st puzzle from guest contributor Gomatamago.

Rules: Shade some cells to make sunglasses. The sunglasses consist of a bridge (a given line, in red) and two lenses made out of orthogonally connected black cells that are symmetric with respect to the perpendicular bisector of the bridge. Two lenses may not share an edge, but can intersect at a point. Cells with the bridges are not shaded, except at the bridge ends. The numbers on the right and bottom edges of the grid indicate the number of shaded lens cells in that row or column.

Also see this example:

Answer String: Enter the length in cells of each of the black lens segments from left to right for the marked rows, starting at the top. Separate each row’s entry with a comma. This example has the key “22,121,12”.

Time Standards (highlight to view): Grandmaster = 5:30, Master = 9:15, Expert = 18:30

Solution: PDF

Note: Follow this link for other shading puzzles.

PDF

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

Theme: Bridge Symmetry and Logic

Author/Opus: This is the 1st puzzle from guest contributor Yuki Kawabe.

Rules: Shade some cells to make sunglasses. The sunglasses consist of a bridge (a given line, in red) and two lenses made out of orthogonally connected black cells that are symmetric with respect to the perpendicular bisector of the bridge. Two lenses may not share an edge, but can intersect at a point. Cells with the bridges are not shaded, except at the bridge ends. The numbers on the right and bottom edges of the grid indicate the number of shaded lens cells in that row or column.

Also see this example:

Answer String: Enter the length in cells of each of the black lens segments from left to right for the marked rows, starting at the top. Separate each row’s entry with a comma. This example has the key “22,121,12”.

Time Standards (highlight to view): Grandmaster = 3:00, Master = 3:45, Expert = 7:30

Solution: PDF

Note: Follow this link for other shading puzzles.

PDF

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

Theme: Logical

Author/Opus: This is the 1st puzzle from guest contributor Eden.

Rules: Shade some cells to make sunglasses. The sunglasses consist of a bridge (a given line, in red) and two lenses made out of orthogonally connected black cells that are symmetric with respect to the perpendicular bisector of the bridge. Two lenses may not share an edge, but can intersect at a point. Cells with the bridges are not shaded, except at the bridge ends. The numbers on the right and bottom edges of the grid indicate the number of shaded lens cells in that row or column.

Also see this example:

Answer String: Enter the length in cells of each of the black lens segments from left to right for the marked rows, starting at the top. Separate each row’s entry with a comma. This example has the key “22,121,12”.

Time Standards (highlight to view): Grandmaster = 1:30, Master = 2:15, Expert = 4:30

Solution: PDF

Note: Follow this link for other shading puzzles.

PDF

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

Theme: No 2×2 White Blocks

Author/Opus: This is the 5th puzzle from guest contributor Jamie Hargrove.

Rules: Shade some cells black so that all unshaded number and arrow clues indicate the exact count of shaded cells in the given direction. Shaded cells cannot share an edge, and all white cells must remain connected as part of a single contiguous group. It is allowed to shade over some of the numbered cells; a shaded over clue may or may not be true. Also, as an extra rule from standard Yajisan Kazusan, there cannot be any fully unshaded 2×2 cell blocks in the grid.

Answer String: For each row from top to bottom, enter the number of shaded cells as a single string.

Time Standards (highlight to view): Grandmaster = 5:00, Master = 12:00, Expert = 24:00

Solution: PDF

Note: Follow this link for other less common Shading puzzles.

PDF

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

Theme: 2×2 Clue Blocks

Author/Opus: This is the 3rd puzzle from guest contributor Jamie Hargrove.

Rules: Shade some cells black so that all unshaded number and arrow clues indicate the exact count of shaded cells in the given direction. Shaded cells cannot share an edge, and all white cells must remain connected as part of a single contiguous group. It is allowed to shade over some of the numbered cells; a shaded over clue may or may not be true.

Also, see this example:

Answer String: For each row from top to bottom, enter the number of shaded cells as a single string. For the example, the answer is “20212”.

Time Standards (highlight to view): Grandmaster = 4:00, Master = 5:15, Expert = 10:30

Solution: PDF

Note: Follow this link for other less common Shading puzzles.

(Note: This bonus puzzle is at a Saturday+ difficulty, and is being posted today to mark the occasion of Prasanna’s birthday.)

(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: 26 on 03/02

Author/Opus: This is the 152nd puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: This puzzle combines Yajisan-Kazusan with Tapa with additional rules.

Left grid = Yajisan-Kazusan (No 2×2): Shade some cells black so that all unshaded number and arrow clues indicate the exact count of shaded cells in the given direction (all counts extend through gaps in the grid). Shaded cells cannot share an edge, and all white cells must remain connected as part of a single contiguous group. It is allowed to shade over some of the numbered cells; a shaded over clue may or may not be true. Also, no 2×2 area inside the grid can be fully white.

Right grid = Tapa: Shade some empty cells black to create a single connected wall. Numbers in a cell indicate the length of consecutive shaded blocks in the neighboring cells. If there is more than one number in a cell, then there must be at least one white (unshaded) cell between the black cell groups. Cells with numbers cannot be shaded, and the shaded cells cannot form a 2×2 square anywhere in the grid.

Additional rule 1: Clues in the middle of the grids indicate the sum or the difference of the number of shaded cells in that row between the grids (possibly both).

Additional rule 2: The shading of the green outlined regions is equivalent in the two grids in the shared cells (if the cell labeled “A” in the illustration below is shaded in one grid it must be shaded in both grids). Note that the 3 and 2 share all locations except for the bottom vertical stem of the numbers which is shifted.

Answer String: For each marked row, enter the length in cells of each of the unshaded segments from left to right in the Yajisan-Kazusan followed by the length of each of the shaded segments from left to right in the Tapa. Separate each row’s entry from the next with a comma (but do not use commas in between the Yajisan-Kazusan and Tapa entry parts in a given row). Enter both digits for any two-digit large segment in an entry.

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

Solution: PDF

PDF

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

Theme: No Obvious Lies (for Jamie Hargrove)

Author/Opus: This is the 53rd puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Shade some cells black so that all unshaded number and arrow clues indicate the exact count of shaded cells in the given direction. Shaded cells cannot share an edge, and all white cells must remain connected as part of a single contiguous group. It is allowed to shade over some of the numbered cells; a shaded over clue may or may not be true.

Also, see this example:

Answer String: For each row from top to bottom, enter the number of shaded cells as a single string. For the example, the answer is “20212”.

Time Standards (highlight to view): Grandmaster = 2:00, Master = 3:15, Expert = 6:30

Solution: PDF

Note: Follow this link for other less common Shading puzzles.

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: Clue Symmetry and Logic

Author/Opus: This is the 131st puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: (Variation of Cave/Shading Puzzles). Shade some empty cells black to create a single connected group. Cells with numbers cannot be shaded, and the shaded cells cannot form a 2×2 square anywhere in the grid. Each numbered cell indicates the total count of shaded cells connected vertically and horizontally to that numbered cell.

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 = 8:00, Master = 11:00, Expert = 22:00

Solution: PDF

Note: Follow this link for other Cave variations and 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 linex mode where left click+drag draws lines and right click marks X’s)

Theme: Powers of Two

Author/Opus: This is the 37th puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: (Variation of Cave/Shading Puzzles). Shade some empty cells black to create a single connected group. Cells with numbers cannot be shaded, and the shaded cells cannot form a 2×2 square anywhere in the grid. Each numbered cell indicates the total count of shaded cells connected vertically and horizontally to that numbered cell.

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 = 5:30, Master = 7:30, Expert = 15:00

Solution: PDF; a solution video is available here.

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