Make Diagrams
Reversi Puzzle Generator
Build an Othello position, mark the move you mean, and take away two boards: the question and the answer. It works out the legal moves itself.
It knows the rules, so your puzzle cannot be wrong
A diagram editor lets you draw anything, including positions that could never happen and questions with no answer. This one computes the legal moves for whoever is to move, marks them on the board, and refuses to accept anything else as the solution. If the move you had in mind is not offered, it is because Reversi does not allow it — which is worth knowing before the worksheet is printed.
It also tells you how many discs each move turns over. What it will not do is tell you which move is best, because in Reversi the move that flips the most discs is usually the worst one available. Working that out is the puzzle.
Two boards from one position
Set an answer and you get the question board and the solution board — the same position after the move, with every flipped disc ringed and the played square marked. Export each separately as PNG, WebP or SVG, or print the page.
For a worksheet, switch to For paper. The board becomes pale green on white with dark coordinates, which prints legibly and costs a fraction of the toner the screen version would.
The position travels in the link
Nothing is stored on a server. The whole board sits in the address, so copying the link is the same as sending the position — and pasted into a chat, the link previews as the board itself rather than as a generic page.
The notation is the sixty-four character board string that Othello engines pass between each other: X for black, O for white, a hyphen for an empty square, then the side to move. A position from a book or another program usually pastes straight in.
Frequently asked questions
Does it know the rules? Yes, and that is the point. It works out every legal move for the side to move and will only accept one of those as the answer, so a puzzle built here cannot ask for a move that does not exist.
How do I make a puzzle? Place the discs, choose who is to move, then switch to the Answer tool and click the move you mean. You get two boards: the question, and the position after the move with every flipped disc marked.
Does it tell me the best move? No. It shows which moves are legal and how many discs each one flips, but it has no opinion about which is strongest — and in Reversi the move that flips the most is usually the worst one. Choosing the answer is your job.
Can I share a position? The whole position lives in the link, so anybody who opens it sees your board. Nothing is stored on a server. Pasted into a chat, the link previews as the board itself.
What notation does it use? The 64-character board string that Othello programs pass between each other — X for black, O for white, a hyphen for empty — followed by the side to move. It is not our invention, so a position from elsewhere usually pastes straight in.
Is it good for worksheets? Choose For paper and the board prints as pale green on white with dark coordinates instead of the screen colours. Then export SVG for print or PNG for a document.
New to the game? The full Reversi and Othello guide explains why holding more discs in the middle game is usually losing, and you can play it against the computer here. For draughts positions there is the checkers diagram maker.