Minesweeper on the three standard boards or one of your own, with both first-click conventions offered by name: a safe square, or a safe square and its eight neighbours. Flags, question marks, chording and best times.
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Code-breaking puzzle. Guess the secret colour code from black and white pegs, with a live count of the codes still possible. Four difficulties, six modes
Sudoku with a guarantee most generators skip: every puzzle is checked to have exactly one solution before you see it. Difficulty is measured by the techniques a puzzle needs, and hints say why a digit belongs where it does.
Block stacking with the Super Rotation System and its real wall kicks, so a flat I can stand up off the floor, and a 7-bag randomiser so no piece is ever more than twelve away. Hold, ghost piece and Guideline scoring.
Your first click on a beginner board, under the two conventions for what "first click is safe" means.
First click at row 4, column 4
Safe square: only (4,4) is kept clear Safe zone: (4,4) and its eight neighbours are kept clear
Result
Safe square can open a lone number Safe zone opened 39 squares in the test run
The mines are laid on the first click rather than when the board appears, which is what makes the click safe at all. Which squares are protected is a real choice: a safe SQUARE only promises you will not lose on move one and can still leave you guessing straight away, while a safe ZONE guarantees the click opens an area. The rule also sets the mine ceiling, because protected squares cannot hold mines: a 9x9 board takes 72 mines under the zone rule and 80 under the square rule, and the page prints the number. The version before this one used the zone rule silently and clamped its custom mine field only as you typed it: setting 591 mines on a 30x20 board and then shrinking it to 5 rows left the placer drawing random squares forever, and measured under a step budget it placed 91 and then drew five million more without placing one.
Uncover squares while avoiding hidden mines. The number on a square is the number of mines among its eight neighbours, which is arithmetic and is checked as arithmetic here on every board. The first click is safe, and you choose which of the two promises that means: only the square you click, or the square and its eight neighbours.
Every move is an inference from numbers you can see. With the safe zone rule the first click always gives you a region to work from rather than a single number.
A beginner board takes under a minute once you know what you are doing, and the timer makes it a race against yourself.
The densities are 12.3, 15.6 and 20.6 percent, which is why expert feels different in kind rather than merely bigger.
The custom fields go up to 30 by 40. The page tells you the most mines that board can hold, and clamps you to it rather than accepting a request it cannot fill.
9 by 9 with 10 mines, which is 12.3 percent of the board. Under the safe zone rule the first click opened 39 squares in the test run, because none of the nine around it could hold a mine.
591 mines on a 30 by 20 board, then Rows changed to 5. The mine count is now brought down to what a 5 by 20 board can hold; before, the first click asked the placer for 591 mines on 100 squares and it never returned.
Flag a safe square next to a 1, then double-click the 1. The chord is applied because the count matches, and it opens the real mine. That is what trusting a flag means.
The mines are laid on your FIRST click rather than when the board appears. That is what makes the first click safe: the board is empty until then, so nothing has to be moved out of the way afterwards.
Which squares are protected is a real choice and both conventions exist. A safe SQUARE promises only that you will not lose on move one; it can still open a lone 3 and leave you guessing immediately. A safe ZONE keeps the eight neighbours clear too, so the first click always opens an area and you always start with something to reason about, which is what most modern versions do. The setting says which is in force and switching it deals a new board, because the mines of a game already under way were laid under the old promise and cannot retroactively satisfy the new one.
The rule also decides how many mines a board can hold. Under the zone rule a click in the middle keeps nine squares clear, so a 9 by 9 board tops out at 72 mines; under the square rule only one is kept clear and the same board takes 80. The page prints the ceiling for the board and rule in force, and the custom fields are clamped against it whenever ANY of the three numbers changes.
That last point used to be the sharp edge. The Mines field was clamped as you typed it and never again, so setting 591 mines on a 30 by 20 board and then changing Rows to 5 left a request for 591 mines on 100 squares. The placer drew squares at random and rejected the ones already mined, until it had placed them all; with fewer squares than mines that loop cannot end, and nothing in its body could make it end. Measured on 2026-09-07 under a step budget, it placed 91 of the 591 and then drew five million more squares without placing one. The page stopped responding. Placement now lists the squares a mine is allowed on, shuffles them and takes the first n, which is uniform, costs the same at any density, and cannot fail to finish; a request that will not fit is refused with the numbers in the message.
Chording, opening every unflagged neighbour of a number whose flags already match it, is the one move that can lose a game you were playing correctly, because it trusts your flags rather than checking them. It is refused by name when the flags do not add up, and it goes ahead when they do, wherever they are.
Yes, and you choose what that means. The mines are not laid until you click, so the square you click is never a mine. Under the Safe zone rule its eight neighbours are clear too, so the click always opens an area; under Safe square only the square itself is protected.
Eight, when all eight neighbours are mines. Edge squares can reach five and corner squares three, because they have fewer neighbours to count.
Because they would not fit. Some squares have to stay clear for the first click, so the ceiling is the board size minus the protected zone: 72 on a 9x9 under the zone rule, 80 under the square rule. The page prints the number for the board you are on, and re-clamps it whenever you change the rows or columns as well as the mines.
No. You win by opening every square that is NOT a mine. Flags are a note to yourself and a way to enable chording; the game does not check them.
It chords: if the flags around that number already equal it, every other neighbour is opened at once. It trusts your flags, so if one of them is wrong it opens a mine and the game ends. That is the trade and it is the fastest way to clear a board.
Yes. Minesweeper boards are not generated to be guess-free, so a position can arise where two arrangements are both consistent with everything visible. The safe zone rule removes the worst case, which is being made to guess on move one.
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