How to Play Neutron
Neutron, designed by Robert A. Kraus in 1978, is a small game of sliding pieces where one neutral piece decides everything.
The rules
- The board is 5×5. White's five pieces fill the bottom row, Black's the top row; the neutron starts in the centre. White moves first.
- All pieces, including the neutron, slide in any of the eight directions as far as they can, stopping only when they reach another piece or the edge. A piece must move at least one square.
- A turn has two parts: first move the neutron, then move one of your own pieces. White's very first turn skips the neutron and moves a piece only.
- You win when the neutron comes to rest on your home row, whoever moved it there. If you cannot move the neutron at the start of your turn, you lose.
Playing on kawu
When the neutron must move, its destinations are marked at once; tap one. Then tap one of your pieces and its destination. Home rows are shaded. Hint shows the hard computer's move. Play either colour against three levels, or two players on one device. Undo is allowed.
Next: Neutron strategy.
Frequently asked questions
Can I stop a sliding piece partway?
No. Every piece, the neutron included, slides until something blocks it: another piece or the edge of the board. That is what makes the game sharp.
What if the only neutron moves go to my opponent's home row?
You must still move it, and your opponent wins. Part of the game is leaving your opponent only bad neutron moves.
Last updated 2026-10-21