This year, we are going to have 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 first Sunday Stumper is a challenging Sudoku variation in the style of some of the unusual rule mash-ups and difficulty seen on the Cracking the Cryptic channel.

PDF

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

Theme: Have a Cracking New Year!

Author/Opus: This is the 371st puzzle from Thomas Snyder, aka Dr. Sudoku.

Rules: Standard Sudoku rules. Some arrow shapes are in the grid; the sum of the digits along the path of each arrow must equal the digit in the circled cell (digits can repeat on an arrow). Some thermometer shapes are in the grid; the digits along the thermometer must be strictly increasing from the round bulb to the flat end. Some rectangular cages are in the grid marked by dashed lines; the sum or product of the digits in these cages must be either 20 or 21. Finally, some arrows are given outside the grid; the sum or product of the digits along these marked diagonals must be either 20 or 21 (digits can repeat on a diagonal).

Difficulty: 5 stars

Time Standards (highlight to view): Grandmaster = 15:00, Master = 30:00, Expert = 60:00

Solution: PDF; a solution video from Cracking the Cryptic is here.

Note: Follow this link for other variations on Sudoku.

PDF

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

Theme: 2021

Author/Opus: This is the 187th puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Variation of Skyscrapers; each clue represents the sum of the heights of the visible buildings in that direction.

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 5:00, Master = 11:00, Expert = 22:00

Solution: PDF; a solution video 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.

PDF

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

Theme: 2020

Author/Opus: This is the 3rd puzzle from guest contributor Jonas Gleim.

Rules: Standard Fillomino rules. Also, it must be possible to shade some polyominoes black so that no bordering polyominoes are the same color (in other words, the grid must allow a two-color shading).

See also this example:

Difficulty: 4 stars

Time Standards (highlight to view): Grandmaster = 8:30, Master = 15:00, Expert = 30:00

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

Note: Follow this link for classic Fillomino and this link for Fillomino variations. If you are new to this puzzle type, here are our easiest Fillomino puzzles to get started on. More Fillomino puzzles can be found in The Art of Puzzles, in Fill o’ Fillomino and Fill o’ Fillomino 2 by Grant Fikes, and in our beginner-friendly books Logic Puzzles 101 and Starter Pack 1: Fillomino.

PDF

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

Theme: Double “LITS”

Author/Opus: This is the 22nd puzzle from guest contributor Joseph Howard.

Rules: Standard LITS rules, except that each region must contain two shaded tetrominoes. These two tetrominoes within a region cannot touch each other, and can be the same or different shapes.

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 4:45, Master = 6:45, Expert = 13:30

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

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.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab key to alternate between loop drawing and star placement modes.)

Theme: Edge Cases

Author/Opus: This is the 193rd puzzle from our contributing puzzlemaster Prasanna Seshadri.

Rules: Standard Masyu rules. Also, each row and column must contain exactly two stars. Stars cannot be placed in adjacent cells that share an edge or corner, and all stars must be on empty cells which are not part of the loop.

Difficulty: 3 stars

Time Standards (highlight to view): Grandmaster = 3:45, Master = 5:15, Expert = 10:30

Solution: PDF

Note: Follow this link for classic Masyu and this link for Masyu variations. Follow this link for other classic Star Battles and this link for Star Battle variations.

PDF

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

Author/Opus: This is the 332nd puzzle from our contributing puzzlemaster Grant Fikes.

Rules: Variation of Kakuro. Some 2×2 white regions are to be shaded gray and treated as single (2×2) cells in the Double Kakuro, the position of these cells must be found while solving, and each gray cell is to be filled by a single digit which sits in multiple rows and columns. No digits can repeat within an entry, regardless of whether they are in small or large cells.
(An example Double Kakuro puzzle is linked.)

Difficulty: 2.5 stars

Time Standards (highlight to view): Grandmaster = 3:30, Master = 5:00, Expert = 10:00

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

Note: Follow this link for classic Kakuro and this link for Kakuro variations. More Kakuro puzzles can be found in Kakuro and Variations by Serkan Yürekli and in The Art of Puzzles 2.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode, shape (star) placing mode, and the linex mode where left click+drag draws lines and right click marks X’s)

Theme: White Hole

Author/Opus: This is the 306th puzzle from our managing editor Serkan Yürekli.

Rules: Standard Balance Loop rules. Also, each row and column must contain exactly two stars. Stars cannot be placed in adjacent cells that share an edge or corner, and all stars must be on empty cells not used by the loop.

Difficulty: 4.5 stars

Time Standards (highlight to view): Grandmaster = 13:00, Master = 18:30, Expert = 37:00

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

Note: Follow this link for other Balance Loop puzzles. If you are new to this puzzle type, here are our easiest Balance Loop Puzzles to get started on. More Balance Loops can be found in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli and in Balance Loop by Prasanna Seshadri and Murat Can Tonta.

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: Pairs

Author/Opus: This is the 184th puzzle from our contributing puzzlemaster Murat Can Tonta.

Rules: Standard Balance Loop rules. Also, numbers outside the grid show the number of separate loop segments visible in that direction. A segment of length N in a given direction is taken as a building of height N. Buildings of height N block the view of all buildings behind them of equal or lesser height.

Also, see this example:

Difficulty: 3.5 stars

Time Standards (highlight to view): Grandmaster = 4:30, Master = 7:00, Expert = 14:00

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

Note: Follow this link for other Balance Loop puzzles. If you are new to this puzzle type, here are our easiest Balance Loop Puzzles to get started on. More Balance Loops can be found in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli and in Balance Loop by Prasanna Seshadri and Murat Can Tonta.

Yajilin and Battleships are two of our favorite Loop and Object Placement puzzles, respectively. What happens when you combine them? Our new e-book Yajilin Battleships by Serkan Yürekli will show you.

We’ve included here the example puzzle from the book which is now available for purchase. We have a companion solving video if you want to see what these puzzles are sometimes like. Some other prior posts with this style from Serkan, Freddie Hand and Grant Fikes are linked.

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between Battleships placement and line drawing modes.)

Rules: Variation of Battleships and Yajilin. Place the fleet of ships in the grid so that different ships are not in adjacent cells that share an edge or corner. The grid contains internal clues (a number and an arrow) that show how many ship segments are in the indicated direction. All remaining white cells that do not contain a ship segment must be able to form a single loop, as in a Yajilin puzzle.

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