Kuromasu (nibble.games)

Kuromasu is a grid logic puzzle, and nibble.games gives you one a day, numbered. The board is 9 cells wide and 12 tall. Some cells hold numbers. You fill the rest of the board with teal or black cells under three rules: all teal cells must connect into one area, black cells cannot touch each other side by side, and no teal cell may be cut off.

The numbers do the work. Each one tells you how many teal cells it can see in a straight line, up, down, left and right, counting itself, before a black cell or the edge of the board stops the view. A small number beside it shows how many more teal cells it still needs. If a move makes the puzzle impossible, the cells turn red, so you find out early.

Counters at the top show how many black cells you have placed out of the total, and how many teal cells. There are three reveals, each showing one square, plus Undo and Start Over buttons. The game's advice is to use reveals sparingly. Any valid solution with the right number of black and teal cells scores 100 percent, and when you finish, a summary shows your score and time, with a button to share it.

Each day's grid is built from the puzzle number, which counts the days since 31 January 2025, so everyone who opens the page that day gets the same board. The help box points to a video, and its first 90 seconds give the full rules.