Canvas
Yes. The grid is empty. This puzzle was a collaboration with Crusader175 building on some of the ideas from Cross About Dominoes. This puzzle also appears in the Heartburn Collection.
Estimated difficulty: 4/5
Rules
Normal sudoku rules apply: every row, column, and box contains a complete set of the digits 1-9.
The finished grid contains the minimum number of friendly cells, i.e. cell that contain digits which match at least one of the row, column, or box number.
Every diagonal of length 7 or more is either an entropic line or an isotropic line. On entropic lines, every set of three sequential digits must contain a low digit (1,2,3), a middle digit (4,5,6), and a high digit (7,8,9). On isotropic lines, all digits are from the same entropic rank (low/middle/high).
Each cell is orthogonally adjacent to at least one cell whose digit has a difference of at least 4 with the digit in the original cell.
Solve in the Sudokupad app with solution checker
Losing Our Religion
Straightforward scanning and killer cage practice. This puzzle also appears in our GAS Collection. The title is a nod to the fact that none of our threes in the corner ever get a song from Simon Anthony.
Estimated difficulty: 1.5/5
Rules
Normal sudoku rules apply: every row, column, and box contains a complete set of the digits 1-9.
Killer cages: digits inside cages marked by dashed lines cannot repeat and must sum to the value shown in the upper left corner of the cage.
Solve in the Sudokupad app with solution checker
Point Break
Straightforward scanning and killer cage practice. This puzzle also appears in our GAS Collection.
Estimated difficulty: 1.5/5
Rules
Normal sudoku rules apply: every row, column, and box contains a complete set of the digits 1-9.
Killer cages: digits inside cages marked by dashed lines cannot repeat and must sum to the value shown in the upper left corner of the cage.
Solve in the Sudokupad app with solution checker
IKEA Skylines
A follow-up to Residual Skylines, this puzzle uses hidden modular lines instead of an entropic condition for building skyscrapers. It also appears in our Indigestion Collection 2.
Estimated difficulty: 3/5
Rules
Normal sudoku rules apply: every row, column, and box contains a complete set of the digits 1-9.
The value of each cell gives the height of the skyscraper occupying that cell. Taller skyscrapers hide smaller skyscrapers. Clues outside the grid indicate the number of skyscrapers seen along that row or column from the direction of the clue. The skyscrapers between the clue and the tallest skyscraper in that sightline form a modular line, including the tallest skyscraper and hidden buildings as part of the modular line.
On modular lines, every set of three contiguous cells contains one digit from {147}, one from {258}, and one from {369}.
Solve in the Sudokupad app with solution checker
Restricted Skylines
This puzzle arose from finding different constraints that produce strong patterns in the entire grid. It was featured by BremSter Puzzles on 27 September 2022. It also appears in our GAS Collection.
Estimated difficulty: 1.5/5
Rules
Normal sudoku rules apply: every row, column, and box contains a complete set of the digits 1-9.
Killer cages: digits inside cages marked by dashed lines cannot repeat and must sum to the value shown in the upper left corner of the cage.
Each digit in the grid is a "skyscraper" whose height is the digit in that cell. Taller skyscrapers obscure the view of smaller ones. Clues outside the grid tell how many skyscrapers are visible looking across the row or column from the direction of the clue.
Isotropic groups: Each group of nine cells occupying the same relative position in the nine boxes is isotropic: all nine are from {123} or all nine are from {456} or all nine are from {789}.
