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or solve online (using our beta test of Penpa-Edit tools; in default linex mode: left-click+drag draws line, right click marks X on edge)

Theme: Speed of Light and Speed of Sound

Author/Opus: This is the 20th puzzle from guest contributor Bryce Herdt.

Rules: Draw a single loop in the grid which may cross itself orthogonally, but otherwise does not touch or retrace itself. The clue numbers to the left/right of the rows indicate the number of squares visited by the nearest section of the loop that travels horizontally in the rows. The clue numbers to the top/bottom of the columns indicate the number of squares visited by the nearest section of the loop that travels vertically in the columns.

Also, see this example:

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 2:45, Master = 5:15, Expert = 10:30

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

Note: Follow this link for other Round Trip puzzles. Some more Round Trip puzzles can be found in the book Loop Variety Collection by Ashish Kumar and Murat Can Tonta.

PDF

or solve online (using our beta test of Penpa-Edit tools; in default linex mode: left-click+drag draws line, right click marks X on edge)

Theme: 345

Author/Opus: This is the 393rd puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Draw a single loop in the grid which may cross itself orthogonally, but otherwise does not touch or retrace itself. The clue numbers to the left/right of the rows indicate the number of squares visited by the nearest section of the loop that travels horizontally in the rows. The clue numbers to the top/bottom of the columns indicate the number of squares visited by the nearest section of the loop that travels vertically in the columns.

Also, see this example:

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 2:45, Master = 4:45, Expert = 9:30

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

Note: Follow this link for other Round Trip puzzles. Some more Round Trip puzzles can be found in the book Loop Variety Collection by Ashish Kumar and Murat Can Tonta.

PDF

or solve online (using our beta test of Penpa-Edit tools; in default linex mode: left-click+drag draws line, right click marks X on edge)

Theme: Prime Time

Author/Opus: This is the 354th puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Draw a single loop in the grid which may cross itself orthogonally, but otherwise does not touch or retrace itself. The clue numbers to the left/right of the rows indicate the number of squares visited by the nearest section of the loop that travels horizontally in the rows. The clue numbers to the top/bottom of the columns indicate the number of squares visited by the nearest section of the loop that travels vertically in the columns.

Also, see this example:

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:45, Master = 2:30, Expert = 5:00

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

Note: Follow this link for other Round Trip puzzles. Some more Round Trip puzzles can be found in the book Loop Variety Collection by Ashish Kumar and Murat Can Tonta.

PDF

or solve online (using our beta test of Penpa-Edit tools; in default linex mode: left-click+drag draws line, right click marks X on edge)

Theme: Number Series

Author/Opus: This is the 216th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Draw a single loop in the grid which may cross itself orthogonally, but otherwise does not touch or retrace itself. The clue numbers to the left/right of the rows indicate the number of squares visited by the nearest section of the loop that travels horizontally in the rows. The clue numbers to the top/bottom of the columns indicate the number of squares visited by the nearest section of the loop that travels vertically in the columns.

Also, see this example:

Difficulty: 1.5 stars

Time Standards (highlight to view): Grandmaster = 1:00, Master = 1:40, Expert = 3:20

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

Note: Follow this link for other Round Trip puzzles. Some more Round Trip puzzles can be found in the book Loop Variety Collection by Ashish Kumar and Murat Can Tonta.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a composite mode for line/edge drawing and a shading mode.)

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

Rules: Standard Spiral Galaxies rules.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 2:00, Master = 3:30, Expert = 7:00

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

Note: Follow this link for classic Spiral Galaxies puzzles on this website and this link for variations on Spiral Galaxies puzzles. If you are new to this puzzle type, here are our easiest Spiral Galaxies Puzzles to get started on. More Spiral Galaxies puzzles can be found in The Art of Puzzles 2.

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or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a composite mode for line/edge drawing and a shading mode.)

Theme: White Hole

Author/Opus: This is the 207th puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Standard Spiral Galaxies rules.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 1:45, Master = 2:45, Expert = 5:30

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

Note: Follow this link for classic Spiral Galaxies puzzles on this website and this link for variations on Spiral Galaxies puzzles. If you are new to this puzzle type, here are our easiest Spiral Galaxies Puzzles to get started on. More Spiral Galaxies puzzles can be found in The Art of Puzzles 2.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a composite mode for line/edge drawing and a shading mode.)

Theme: Down the Middle

Author/Opus: This is the 353rd puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Standard Spiral Galaxies rules.

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:00, Master = 2:30, Expert = 5:00

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

Note: Follow this link for classic Spiral Galaxies puzzles on this website and this link for variations on Spiral Galaxies puzzles. If you are new to this puzzle type, here are our easiest Spiral Galaxies Puzzles to get started on. More Spiral Galaxies puzzles can be found in The Art of Puzzles 2.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a composite mode for line/edge drawing and a shading mode.)

Theme: Triplets

Author/Opus: This is the 78th puzzle from our contributing puzzlemaster Ashish Kumar.

Rules: Standard Spiral Galaxies rules.

Difficulty: 1.5 stars

Time Standards (highlight to view): Grandmaster = 0:50, Master = 1:20, Expert = 2:40

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

Note: Follow this link for classic Spiral Galaxies puzzles on this website and this link for variations on Spiral Galaxies puzzles. If you are new to this puzzle type, here are our easiest Spiral Galaxies Puzzles to get started on. More Spiral Galaxies puzzles can be found in The Art of Puzzles 2.

PDF

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

Theme: It’s T Time

Author/Opus: This is the 215th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Standard Sudoku rules. Also, the sum of the numbers in each cage must equal the value given in the upper-left corner of that cage. Numbers cannot repeat inside a cage.

Difficulty: 4.5 stars

Time Standards (highlight to view): Grandmaster = 11:15, Master = 19:00, Expert = 38:00

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

Note: Follow this link for more Killer Sudoku and this link for classic Sudoku. More Killer Sudoku puzzles can be found in Killer Sudoku by Serkan Yürekli.

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or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: Magic Squares

Author/Opus: This is the 32nd puzzle from our contributing puzzlemaster JinHoo Ahn.

Rules: Place the digits in the indicated range (1-9) in some of the cells so that no digit is repeated in any row or column. Numbers on the outside of the grid indicate the sums of adjacent digit groups in that row or column, in order. Each sum is separated by at least one unused cell.

Difficulty: 4.5 stars

Time Standards (highlight to view): Grandmaster = 7:15, Master = 20:00, Expert = 40:00

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

Note: Follow this link for other Japanese Sums puzzles.