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or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Surface = shading mode and a line drawing mode)

Theme: All Threes

Author/Opus: This is the 27th puzzle from guest contributor Joseph Howard.

Rules: Standard Cave rules. (The puzzle is on a hexagonal grid and cells now see in a maximum of six possible directions.)

Difficulty: 2.5 stars

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

Solution: PDF; a solution video is also available here.

Note: Follow this link for classic Caves and this link for Cave variations. If you are new to this puzzle type, here are our easiest Cave Puzzles to get started on. More Cave puzzles can be found in Roger Barkan’s Colossal Cave Collection, in The Art of Puzzles, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

PDF

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

Theme: Knight Steps

Author/Opus: This is the 15th puzzle from our new contributing puzzlemaster JinHoo Ahn.

Rules: Variation of Cave rules. Instead of their usual meaning, interior clues indicate the number of shaded cells in neighboring cells, including diagonally adjacent cells. Cells with numbers cannot be shaded.

See also this example:

Difficulty: 3 stars

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

Solution: PDF; a solution video (with info on an Easter Egg for this puzzle) is also available here.

Note: Follow this link for other classic Caves and this link for Cave variations. If you are new to this puzzle type, here are our easiest Cave Puzzles to get started on. More Cave puzzles can be found in Roger Barkan’s Colossal Cave Collection, in The Art of Puzzles, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

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Theme: 3×3 Squares

Author/Opus: This is the 189th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Standard Cave rules. Also, exactly one digit is a joker wherever it appears; each instance of it may be replaced by any nonzero number, like a “?” clue.

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 2:45, Master = 5:00, Expert = 10:00

Solution: PDF

Note: Follow this link for other classic Caves and this link for Cave variations. If you are new to this puzzle type, here are our easiest Cave Puzzles to get started on. More Cave puzzles can be found in Roger Barkan’s Colossal Cave Collection, in The Art of Puzzles, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

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Theme: Clue Symmetry and Logic

Author/Opus: This is the 264th puzzle from our contributing puzzlemaster Serkan Yürekli.

Rules: Standard Cave rules. (The puzzle is on a hexagonal grid and cells now see in a maximum of six possible directions.)

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 = 4:45, Master = 6:45, Expert = 13:30

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. More Cave puzzles can be found in Roger Barkan’s Colossal Cave Collection, in The Art of Puzzles, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

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Theme: Clue Symmetry and Logic

Author/Opus: This is the 198th puzzle from our contributing puzzlemaster Serkan Yürekli.

Rules: Standard Cave rules; also, all groups of cells outside the Cave must be formed out of different arrangements of exactly five cells (i.e., different pentominoes). Pentomino shapes may be reflected or rotated, but they cannot repeat or touch each other. Not all pentominoes need to appear.

This example uses four cell regions (i.e., tetrominoes) within the same rules.

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 = 6:45, Master = 11:45, Expert = 23:30

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. More Cave puzzles can be found in The Art of Puzzles and in Roger Barkan’s Colossal Cave Collection.

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Theme: Sunken Lake

Author/Opus: This is the 54th puzzle from our contributing puzzlemaster John Bulten.

Rules: This puzzle is a combination of Cross the Streams and Cave rules (with the exception of having multiple “caves” that all connect to the edge of the grid).

Shade some empty cells black to create a single group of black cells that are all connected to each other through their edges. No 2×2 cell area within the grid contains all black cells. Numbers to the left/top of the grid represent the groups of consecutive black cells which are in that row/column in order, either from left to right or from top to bottom. A question mark (?) represents a group of consecutive black cells whose size is unknown; an asterisk (*) represents any number of unknown groups of black cells, including none at all.

All white cells must be connected via other white cells to an edge of the grid. All numbered cells inside the grid must be white and each number in these cells indicates the total count of white cells connected vertically and horizontally to the numbered cell including the cell itself.

See also this example:

Answer String: Enter the length in cells of each of the (white) 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 = 3:30, Master = 4:30, Expert = 9:00

Solution: PDF

Note: Follow this link for other Cross the Streams. Follow this link for other Cave variations and this link for other classic Caves. If you are new to Cave puzzles, here are our easiest Cave Puzzles to get started on. More Cave puzzles can be found in The Art of Puzzles and in Roger Barkan’s Colossal Cave Collection.

(Note: This bonus puzzle is being posted today to mark the occasion of Prasanna’s birthday.)

(View image directly for larger form.)

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Theme: 27 years from 03-02-1991 to 03-02-2018

Author/Opus: This is the 160th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: (This puzzle uses standard “Canal View” rules.) 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.

Also, in addition to standard Canal View rules, the clues outside the grid on the top and left indicate the difference in lengths of the largest and smallest shaded groups in that row/column (the smallest group must be >0 cells in size and there must be at least two groups in that row/column). The clues outside the grid on the bottom and right indicate the number of shaded groups in that row/column. All ? clues must stand for prime numbers (2, 3, 5, 7, …).

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 = 10:00, Master = 22:00, Expert = 44:00

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.