50/50 in Minesweeper
In classic Minesweeper the mines are placed at random, and sometimes the numbers honestly have no answer. The most common case is two covered cells, one mine, and both neighboring numbers see both cells. That is a 50/50: no amount of staring will give you more information.
Where 50/50s usually show up
- Two cells in a corner or against a wall that are seen by exactly the same numbers, like the picture above.
- A 2×2 square with two mines on a diagonal: the surrounding numbers fit either layout equally well.
- A long one-cell-wide corridor between mines, where every number sees the same pair.
The more mines on the board, the more of these spots you get: far fewer Expert boards can be finished without a guess than Beginner ones. That is why Expert records come from long sessions of games rather than a single lucky one.
Is it a real 50/50?
Before you guess, check three things. Is there a number nearby that sees only one of the two cells? Does the area resolve once you subtract flags? Does the mine counter help? Near the end of a game, the number of mines left sometimes decides the layout. If none of that works, you will have to guess.
Guess less, guess smarter
- Guess early, not late. If a 50/50 is visible now, click it now: losing at second ten hurts less than losing three minutes in, and the odds are the same.
- Finish everything that logic can solve elsewhere first. A new number on the other side sometimes settles the question.
- If the choice is between several cells rather than two, pick the one with the lower mine chance that will reveal the most, usually a cell on the edge of the open area rather than deep in the covered part.
The no-guessing mode
The No-guessing toggle above the board changes the generator. Every board is checked by a solver before you see it, and only boards that can be cleared by logic from the first click make it into the game. There are no 50/50s there at all. If it looks like you are stuck, there is a deduction, just a harder one: the Hint button shows the cell and the technique level, whether one number, two numbers or a full search.
These boards are great for learning, because a loss always means a mistake in your reasoning rather than bad luck. The Evil level, 30×20 with 130 mines, is picked so that you can't get through it without the full search. And every fight in the arena is played on no-guess boards, otherwise a coin flip would decide the winner.