Minesweeper

Minesweeper hides mines under a grid of tiles and gives you one tool to find them: the numbers. Open a safe square and it tells you how many of its eight neighbours are mined. Zero, and the empty area unfolds outwards on its own, handing you a whole region for free. Everything after that is deduction, one square at a time.

Three boards, three moods. Beginner is nine by nine with ten mines, a two-minute puzzle you can solve on a coffee break. Intermediate doubles the grid and quadruples the danger. Expert is thirty by sixteen with ninety-nine mines and no room for a careless click. Your first click is always safe on every board, so no run is over before it starts, and the clock only starts when you open the first square.

Left click opens, right click plants a flag, and clicking a number that already has all its flags opens the rest of its neighbours in one move. On a phone, tap to open, hold for 450 milliseconds to flag, or switch on flag mode and tap away; the Expert board pans under your finger and pinches to zoom. The timer, the mine counter and your best time per board are all in the browser, and the only thing standing between you and a clean sweep is the square you cannot quite work out.