Diffinity

About Diffinity

Diffinity, also titled 差ピクロス in Japanese, is a number logic puzzle by Cuprum Legion that runs in the browser on itch.io. The page pitches it to players who enjoy sudoku, Picross or Kakuro and calls it a new kind of logic puzzle.

The board is a 5x5 grid to fill with numbers from 1 to 6. Beside each row and above each column is a list of four numbers: the differences between neighbouring cells, read from left to right or top to bottom. A row clued 2, 3, 1, 4 has neighbours that differ by 2, then 3, then 1, then 4. A few cells start filled in, and from those and the difference lists you work out the rest. The page says every puzzle has a unique solution and can be solved by logic alone.

The calendar button starts the daily puzzle. It is built from the day's date, so players on the same difficulty get the same board, and each puzzle has a problem ID that can be typed into the Load box to replay it. The START button generates a fresh random puzzle at any of five star levels, which differ in how many cells are fixed (five at one star, three from three stars up).

A timer runs while you play, the game counts mistakes and chains of logical moves, and there are Hint, Check and Reset buttons. Favourites and a history of solved puzzles are kept in the browser. The game opens in Japanese and switches to English with the flag button; it is built to work on phones.

How to play Diffinity

1. Open the game on itch.io and switch to English with the flag button if needed.
2. Pick a difficulty and press the calendar button to start the daily puzzle.
3. Read the difference lists beside each row and above each column: each number is the gap between two neighbouring cells.
4. Tap a cell and enter a number from 1 to 6, starting from the fixed cells and working outward.
5. Fill the whole grid so every row and column matches its differences; use Check or Hint if stuck.

Screenshots

Tips

• A difference of 5 can only be 1 next to 6, so those clues pin cells down fast.
• Practise on one or two stars, where five or four cells are fixed, before the harder levels with three fixed cells.
• Next to a fixed cell, a difference leaves at most two options (the number plus or minus the gap), and often only one fits between 1 and 6.
• Cross-check each cell against both its row and its column lists before committing.

Questions