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

Theme: Pinwheel

Author/Opus: This is the 19th puzzle from our contributing puzzlemaster JinHoo Ahn.

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

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 4:00, Master = 10:00, Expert = 20:00

Solution: PDF; two solution videos are also available here (more complex path) and here (simpler path).

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 books Star Battle by JinHoo Ahn and Star Battle 2 by JinHoo Ahn and Murat Can Tonta, and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

This is a bonus Sunday puzzle for Valentine’s Day, and one more puzzle to conclude a full week of puzzles from JinHoo Ahn.

PDF

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

Theme: Valentine

Author/Opus: This is the 18th puzzle from our contributing puzzlemaster JinHoo Ahn.

Rules: Standard Masyu rules. Also, some white circles may be shaded to become black circles. (Stylistically, here the white circles are white with red borders and the black circles are filled, red circles.)

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 3:30, Master = 8:00, Expert = 16:00

Solution: PDF

Note: Follow this link for other Masyu variations and this link for classic Masyu. If you are new to this puzzle type, here are our easiest Masyu to get started on. More Masyu puzzles can be found in The Art of Puzzles.

PDF

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

Theme: Groups

Author/Opus: This is the 17th puzzle from our new contributing puzzlemaster JinHoo Ahn.

Rules: Variation of Cross the Streams rules. Instead of their usual meaning, clues refer to the distribution of the white cells. The shaded cells must still obey the regular rules (connectivity, no 2×2 squares).

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 6:30, Master = 10:30, Expert = 21:00

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

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

PDF

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

Theme: Open Middle

Author/Opus: This is the 16th puzzle from our new contributing puzzlemaster JinHoo Ahn.

Rules: Variation of Yajilin rules. Instead of their usual meaning, interior clues refer to the total sum of the lengths of loop segments in the given direction. (An equivalent way to understand these values is to count the number of cell borders crossed by the loop in that direction.)

See also this example:

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 3:15, Master = 6:00, Expert = 12:00

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

Note: Follow this link for classic Yajilin and this link for Yajilin variations. If you are new to this puzzle type, here are our easiest Yajilin to get started on. More Yajilin puzzles can be found in The Art of Puzzles 2, in Yajilin by Murat Can Tonta and Prasanna Seshadri, and in our beginner-friendly book Logic Puzzles 101.

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

Theme: Double X

Author/Opus: This is the 14th puzzle from our new contributing puzzlemaster JinHoo Ahn.

Rules: Variation of Arrow Sudoku rules. Instead of the usual meaning, the digit in the circled cell of each arrow must equal the product of the digits along the path.

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 3:30, Master = 4:45, Expert = 9:30

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

Note: Follow this link for more Arrow Sudoku. If you are new to this puzzle type, here are our easiest Arrow Sudoku to get started on. More Arrow Sudoku puzzles can be found in The Art of Sudoku 2 and Masterpiece Sudoku Mix 3.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between ship placement and shading modes. In ship placement mode, right click gives sea, left click gives circle/square, left click and drag for rounded ships.)

Theme: Rise and Fall

Author/Opus: This is the 13th puzzle from our new contributing puzzlemaster JinHoo Ahn.

Rules: Variation of Battleships rules. Instead of their usual meaning, exterior clues indicate the length of the first ship seen from the corresponding direction.

See also this example:

Difficulty: 2 stars

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

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

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

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

Theme: Pairs of Clues

Author/Opus: This is the 12th puzzle from our new contributing puzzlemaster JinHoo Ahn.

Rules: Variation of Skyscrapers rules. Instead of their usual meaning, exterior clues indicate the height of one of the visible buildings that can be seen from that direction.

See also this example:

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:15, Master = 2:00, Expert = 4:00

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

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

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

Theme: Cells

Author/Opus: This is the 11th puzzle from guest contributor JinHoo Ahn.

Rules: Standard LITS rules.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 1:45, Master = 3:15, Expert = 6:30

Solution: PDF

Note: Follow this link for classic LITS and this link for LITS variations. If you are new to this puzzle type, here are our easiest LITS to get started on. More LITS puzzles can be found in LOTS O’ LITS by Grant Fikes and Prasanna Seshadri, in The Art of Puzzles 2, 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: Episode V

Author/Opus: This is the 10th puzzle from guest contributor JinHoo Ahn.

Rules: Standard Star Battle rules with two stars per row, column, and region. Also, each given gray line must contain two stars.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 4:00, Master = 7:45, Expert = 15:30

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

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.