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Sunsweeper
Puzzle · Classics · plays in your browser, no download
Every number on the board tells you exactly how many of its eight neighbours are hiding something. From that one fact, and nothing else, almost the entire board can be deduced — and the word almost is doing real work.
Where it comes from
The version everybody knows was written at Microsoft. Curt Johnson made the first one for IBM’s OS/2, where it was called PM Mine (1989); his colleague Robert Donner wrote the Windows version. It shipped in the Windows Entertainment Pack on 8 October 1990, and then — this is the part that mattered — it was included with Windows 3.1, which put it on essentially every office desk in the world.
That bundling was not entirely innocent. The mouse was still new to most people, and the games that came with Windows each taught a different piece of it: Solitaire taught dragging, and Minesweeper taught precise clicking — and, unusually for the time, the right button, which until then many users had never knowingly pressed.
A story that circulates says the game was copied from Mined-Out, a 1983 game for the ZX Spectrum. That is disputed: Johnson has said he took the idea from an earlier game, but not that one. The underlying puzzle is older than any of them in any case — it is a constraint problem, and the version with numbers on a grid turns up in several places before 1990.
One honest thing about the design is worth knowing. Minesweeper is not always solvable by logic. Some boards end with two squares, one mine, and no information anywhere that distinguishes them. Most imitations quietly rig the board to avoid it. Leaving it in is the more truthful choice, and the reason good players talk about the odds on the last move rather than pretending there is a proof.
How to play
| Uncover | Left click, or tap. |
|---|---|
| Flag | Right click, or press and hold on a phone. Marks a square you believe is hiding a sun. |
| The numbers | A number is how many of that square’s eight neighbours hold a sun. Blank means none, and the board opens up by itself. |
| The first click | Always safe. You cannot lose on move one. |
Two patterns do most of the work on any board:
- The number is satisfied. If a 2 already touches two flags, every other square around it is safe. Open them all.
- The number is full. If a 3 has exactly three unopened neighbours left, all three are suns. Flag them all.
Everything harder is those two rules applied to overlapping neighbourhoods: compare what two adjacent numbers can see, and the difference between them tells you about the squares only one of them touches. The classic is 1–2–1 along a wall, which is fully determined every single time.
Our version
Suns instead of mines, several sizes, and the same honest board: no rigging, no re-dealing behind your back.
Three things that help
Work the edges and the corners first. A corner square has three neighbours instead of eight, so the numbers near it carry far more information per square.
Flag less than you think. Flags are a memory aid, not progress. Time spent flagging squares you already know is time not spent on the squares you do not.
When you genuinely must guess, pick the square with the best odds, not the nearest one. Count the ways the remaining suns can be arranged. It is often two-to-one in favour of one square, and that is worth having.