Daily Binairo (SudokuWiki)

Binairo, also known as Takuzu or binary puzzle, is a logic grid that Andrew Stuart's SudokuWiki.org added to its set of daily puzzles. The page offers four boards a day: 6x6 and 8x8 in the plain version, and 6x6 and 8x8 Binairo Plus. Each board shares one puzzle number for the day and comes at three levels, rated one to three stars. Every puzzle has a single solution and can be played on the page or printed.

The rules fit in three lines. No more than two circles of the same colour may sit next to each other in a row or column. Every row and column must hold the same number of black and white circles. In the plain version no two rows and no two columns may be identical; in Plus, an equals sign between two cells means they share a colour and an X means they differ.

A timer runs while you play, and Check and Hint buttons sit beside the board. Level 1 of the 6x6 takes a minute or two; the three-star 8x8 boards ask for longer chains of deduction. Regular solvers discuss each day's numbered boards in the comments below the puzzles, and the author answers there.

It suits players who like LinkedIn's Tango or other no-guessing grids and want more of them every day, at a difficulty they choose.