How to win at Reversi: corners, mobility and patience
5 min read ·
Reversi looks like a race to flip the most discs, and beginners play it that way. But discs change colour all game long; only the last position counts. Strong players think about which squares can never be taken back, and about how many moves each side has left.
This guide covers the ideas that win against Puzzimo's computer at every level, from the corners to the endgame.
The rules
- You play black on an 8×8 board and move first.
- Place a disc so that it traps a straight line of white discs between it and another black disc, across, down or diagonally. All trapped discs flip to black.
- If you have no legal move, you pass. When neither side can move, the player with more discs wins.
- Legal moves are marked with dots.
Corners are everything
A disc in a corner can never be flipped: no line can trap it. Corners also anchor the edges next to them, so a corner often leads to a whole stable edge. Taking a corner is almost always good, and giving one away is almost always bad.
Avoid the squares next to empty corners
- The square diagonally next to a corner (often called the X-square) is the most dangerous move on the board while that corner is empty: it frequently hands the corner to your opponent.
- The two squares beside a corner on the edges (C-squares) are risky too, for the same reason.
- Once a corner is taken, its neighbouring squares are much safer.
Mobility beats disc count
In the opening and middlegame, having more moves available matters more than having more discs. Flipping many discs often gives your opponent more options and leaves you with few. Prefer moves that flip few discs, keep your discs in the middle, and leave the computer with bad choices.
Avoid building long walls of your colour along the outside: they give your opponent lots of discs to trap.
The endgame
In the last dozen moves, disc count finally matters. Count carefully, think about parity (who will get the last move in each empty region), and take the edges and corners that lock in your discs.
Practise
Puzzimo's computer looks one move ahead on Easy, two on Medium and four on Hard. Only wins are ranked, by the number of discs you finish with, so a big win beats a narrow one.
Frequently asked questions
Is Reversi the same as Othello?
Othello is a trademarked version of Reversi with a fixed starting position. Puzzimo's Reversi uses the same standard rules: trap lines of discs to flip them, and most discs at the end wins.
Why shouldn't I flip as many discs as possible?
Because discs keep changing colour. Flipping many early often gives your opponent more moves and you fewer, which leads to losing corners later.
What is an X-square in Reversi?
The square diagonally next to a corner. Playing there while the corner is empty usually lets your opponent take the corner.