SurroundNine (BrainBashers)

SurroundNine is Kevin Stone's own name, trademarked, for the mosaic puzzle type also seen as Fill-a-Pix. The grid is full of grey squares, some of them holding a number from 0 to 9. Each number counts the black squares in the nine-square patch around it: the square itself plus its eight neighbours, diagonals included. You decide square by square which are black and which are white, until every number is right.

BrainBashers posts six sizes every day: 5x5 and 7x7 at Easy, 10x10 and 12x12 at Medium, and 15x15 and 20x20 at Hard, with a 25x25 weekly special. The play page greys out clues that are finished (you can turn that off) and has check, answer, print and restart buttons, an option to show mistakes and an optional clock. Tap a square once for black and again for white. A help page explains the starting patterns with a walkthrough.

The puzzles change at midnight GMT or at your chosen time zone, and the previous four weeks stay in the date list. Random buttons at easy, medium and hard, and a New button on the play page, give extra grids beyond the dated ones. The page carries no adverts and needs no account.

It suits Minesweeper players who enjoy the counting but not the guessing, since every SurroundNine can be solved by logic.