# Puzzle 156: Killer Sudoku

Next weekend I’m running a pure Killer Sudoku contest at logic-masters.de. The idea was to give our Killer Sudoku experts a chance to shine. It’s 9 puzzles in 90 minutes from 6 authors, see the instruction booklet for further details. Thank you to Tom Collyer, Stefan Heine, DavidMcNeill, Eva Schuckert and Bernhard Seckinger for their contribution!

To get you in the mood, here’s one Killer Sudoku.

Rules Solve as a regular Sudoku. In addition, some cages are given. The cage clues indicate the sum of the digits within the cage. Digits can’t repeat within a cage.

# Puzzle 155: Minesweeper-Tapa

Here’s another puzzle I made in preparation for the recent Logic Masters. It’s a Minesweeper Tapa, a type from the Tapa round on the contest.

In other news, results have now been posted: https://logic-masters.de/LM/2018_e_tabelle.php. (It seems linear time bonus really isn’t the right choice where players finish after a fraction of the round: On round 6 I took 3.5 minutes compared to the next player’s 5 minutes, for a factor 1.06 in points.)

Rules Solve as a regular Tapa, except the clues just specify the total number of shaded cells in the surrounding cells, as in Minesweeper.

# Puzzle 153: Friendly Sudoku

Here’s a new (?) Sudoku variant. Inspired by Sudoku N from the upcoming Sudoku Mahabharat. The 6×6 example there also solves uniquely by these rules.

Rules Solve as a regular Sudoku. Some pairs of numbers are friends. Dots mark all spots where two friends are next to each other.

# Puzzle 152: Masyu No-Touch

Another one for the GP. This is a Masyu with the extra rule that unused cells can’t touch by edge.

Solve and check your solution here, or use PZV (but that doesn’t verify the no-touch rule).

# Puzzle 149: Skyscrapers²

The WPC 2017 in Bengaluru is over. Here’s a puzzle from my very thin set of preparation puzzles. It’s from a round with original types that applied the same set of rules “twice over” in a sense.

Rules Solve the grid as a regular skyscrapers puzzle, digits 1 through 5. In addition, small clues in the outer corners are skyscraper clues for the regular skyscraper clues along the outside. These 20 regular syscrapers clues are part of the solution.

For example, the regular skyscraper clues along the left side could be something like 1,3,5,2,2 to satisfy the second-level 3 clue in the top left corner.

Or see the rules of Round 20: Puzzle Fusion in the WPC instruction booklet, available at the WPC page. You can find an example there, too.

You can check your solution and solve online here.

# Puzzle 143: Nanro Signpost

Here’s a Nanro Signpost.

Rules Shade some cells, so that all shaded cells are connected, and such that shaded cells don’t fill any 2×2 square. Clues indicated the number of shaded cells in an area; each area must have at least one shaded cell. Whenever two shaded cells touch across walls, the number of shaded cells within both areas must be different.

# Puzzle 136: External Sudoku

We’re running a small preview series on croco-puzzle for the 2016 WSC and WPC, which will take place in Slovakia soon. We’ll kick it off with an External Sudoku tomorrow. For this, I made an example puzzle which seems worth posting in its own right.

Rules Solve as a standard Sudoku, i.e., fill the grid with numbers 1-8 such that every row, column and outlined area contains each digit exactly once.

In addition, there is a diagonal rectangle of gray cells. Every edge of this rectangle must contain exactly the digits 1-(length of the edge). Diagonally adjacent digits in gray cells must not be consecutive.

Or see the instruction booklet.