Since 2021, we have posted some extra difficult Sunday Stumpers, about once a month. These will be quite tough puzzles, but with a logical path to be found (and solution videos to help). This thirteenth Sunday Stumper of 2022 is an unusual Castle Wall puzzle by Stefan Liew where all the clues are on the “Outside”.

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: Outside

Author/Opus: This is the 3rd puzzle from guest contributor Stefan Liew.

Rules: Standard Castle Wall rules.

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 11:00, Master = 22:30, Expert = 45:00

Solution: PDF and solving video.

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.

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: Hexed

Author/Opus: This is the 423rd puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Castle Wall rules except on a hexagonal grid.

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 15:30, Master = 21:30, Expert = 43:00

Solution: PDF and solving video.

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.

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: Odds

Author/Opus: This is the 378th puzzle from our managing editor Serkan Yürekli.

Rules: Standard Castle Wall rules, but any two consecutive line segments cannot have the same length (i.e., on both sides of any turn, the loop must travel different lengths).

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 6:30, Master = 9:45, Expert = 19:30

Solution: PDF and solving video.

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.

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: Black Window

Author/Opus: This is the 2nd puzzle from guest contributor Stefan Liew. (This particular puzzle was an early and noteworthy puzzle from @stefpuzzle’s daily Castle Wall series that reached 100 total puzzles.)

Rules: Standard Castle Wall rules.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 3:30, Master = 4:30, Expert = 9:00

Solution: PDF and solving video.

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.

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: Black Box

Author/Opus: This is the 57th puzzle from our contributing puzzlemaster JinHoo Ahn.

Rules: Standard Castle Wall rules.

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 2:00, Master = 3:45, Expert = 7:30

Solution: PDF and solving video.

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.

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: Windmill

Author/Opus: This is the 17th puzzle from guest contributor Jonas Gleim.

Rules: Standard Castle Wall rules.

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:15, Master = 2:30, Expert = 5:00

Solution: PDF and solving video.

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.

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: 4×4

Author/Opus: This is the 244th puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Standard Castle Wall rules.

Difficulty: 2 stars

Time Standards (highlight to view): Grandmaster = 1:20, Master = 2:00, Expert = 4:00

Solution: PDF and solving video.

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.

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: Ones

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

Rules: Standard Castle Wall rules.

Difficulty: 1 star

Time Standards (highlight to view): Grandmaster = 0:25, Master = 0:45, Expert = 1:30

Solution: PDF and solving video.

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.

See more discussion of the puzzles from the United States’ 2021 Puzzle Grand Prix on this post. Note there are some construction details and potential spoilers on that post so view it after you solve.

PDF

or solve online (using our beta test of Penpa-Edit tools using a composite mode where left click inside cell shades square, left click + drag draws line segment, right click inside cell adds dot, and right click on cell edge adds an x.)

Author/Opus: This is the 401st* puzzle from Thomas Snyder, aka Dr. Sudoku (*the 400th puzzle opus number is being held for an upcoming post).

Rules: Standard Yajilin rules: Blacken some white cells and then draw a single closed loop (without intersections or crossings) through all remaining white cells. Blackened cells cannot share an edge with each other. Some cells are outlined and in gray and cannot be part of the loop. Numbered arrows in such cells indicate the total number of blackened cells that exist in that direction in the grid.

Also, in addition to the usual gray clues, some clues are white and black and act similarly to Castle Wall clues. White clues must be inside the loop and black clues must be outside the loop. White and black clues indicate the sum of the lengths of loop segments in the indicated direction.

Difficulty: 2.5 stars (estimate based off competition points; timing standards not available from our usual testers)

Solution: PDF

Note: Follow this link for classic Yajilin and this link for Yajilin variations. Follow this link for more Castle Wall puzzles.

See more discussion of the puzzles from the United States’ 2021 Puzzle Grand Prix on this post. Note there are some construction details and potential spoilers on that post so view it after you solve.

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)

Author/Opus: This is the 398th puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Castle Wall rules.

Difficulty: 2 stars (estimate based off competition points; timing standards not available from our usual testers)

Solution: PDF

Note: Follow this link for more Castle Wall puzzles. If you are new to this puzzle type, here are our easiest Castle Wall puzzles to get started on. More Castle Wall puzzles can be found in our beginner-friendly collection Intro to GMPuzzles as well as the larger collection Castle Wall, both by Serkan Yürekli.