Reversi is a game where the position that looks best after ten moves is often the position that loses. Beginners chase captures โ flipping as many discs as possible every turn โ and by move twenty they've handed their opponent the board. Strong Reversi is nearly the opposite: control matters more than material, and disc count only becomes meaningful in the last few moves.
The Rules of Reversi
Reversi is played on an 8x8 grid, starting from a fixed position: two black discs and two white discs on the four center squares, arranged diagonally so each color faces itself. Players alternate turns, black moving first. On each turn, a player must place one disc of their color on an empty square such that it traps one or more opponent discs in a straight line โ horizontal, vertical, or diagonal โ between the new disc and another disc of their own color already on the board. Every opponent disc trapped in that line flips to the player's color immediately.
Reading the Board: Notation and Position
Why Capturing Too Many Discs Early Is a Trap
The single biggest habit that separates new players from everyone else: having the most discs in the early or middle game is not an advantage, and is often a warning sign. A large stack of discs in the open middle is a large target โ every one can be flipped back by a single well-placed move later, since the middle game is exactly when the board's shape is still unsettled.
The practical rule: prefer moves that keep your options open and limit your opponent's, even if a flashier move would flip more discs right now. Disc count only matters in the final handful of moves, once the board is nearly full.
Corners: The Most Valuable Squares on the Board
The four corner squares can never be flipped once claimed โ no line can trap a disc sitting in a corner, because a corner only has neighbors on two sides instead of four or eight. A disc placed in a corner is permanent for the rest of the game, and it anchors every disc built along the two edges running away from it, since those discs become much harder to flip once connected to a secure corner.
X-Squares and C-Squares: The Danger Zones Next to Corners
Each corner has two adjacent edge squares (C-squares) and one diagonally adjacent square (the X-square). These are the most dangerous squares on the board: playing one before the corner is settled frequently hands your opponent the exact opening they need to take that corner next.
The X-square is worst of the three. A disc placed there while the corner is still empty almost always gives the opponent a legal move directly into that corner, and once taken, your X-square disc now anchors their corner instead of yours. The two C-squares carry the same risk in milder form. The habit worth building: don't play a corner's neighboring squares until the corner itself is decided.
Edge Play and Building Stable Discs
Discs along the outer edge are flipped by fewer possible lines than discs in the open middle, which makes edges a good place to build a position that holds up over time. A disc is "stable" once no sequence of legal moves can ever flip it โ discs in a claimed corner are always stable, and discs connected in an unbroken line to a corner are usually stable too, since flipping them would require flipping the corner disc first, which is impossible.
The strongest edge shapes are built outward from a corner you already control, one connected disc at a time, rather than scattered discs placed independently. A scattered edge disc with empty squares on either side is still vulnerable from both directions and offers little of the safety edge play promised.
Parity and the Endgame
As the board fills up, the number of empty squares remaining starts to matter on its own, independent of where they are. This is parity, and it becomes decisive late in a close game. Whoever is forced to move into the last few open regions first is often at a disadvantage, since the opponent gets to respond to whatever shape that move creates.
Finishing the Game: Counting and Final Moves
The game ends when the board is full or neither player has a legal move remaining. Every disc is counted, and whichever color has more wins โ with empty squares, in some variants, awarded to the majority holder. This is the one moment where raw disc count matters, which is why ignoring it earlier feels counterintuitive.
In the final handful of moves, with few empty squares left, calculating the exact result of each option becomes possible, and a player who built a stable position usually finds the endgame straightforward. A player who spent the middle game chasing flips instead of position usually finds the opposite โ a large disc count that collapses as stable corners and edges flip everything else on the board.
Common Mistakes
- Chasing the highest disc count early. A big middle-game lead is often unstable and gets wiped out once your opponent starts flipping it back.
- Playing an X-square or C-square too early. The most common way new players hand a corner to their opponent for free.
- Ignoring mobility. Being forced to pass, or left with only bad moves, is a losing position even with more discs on the board.
- Building scattered edge discs. A disc with open squares on both sides isn't stable and can be flipped from either direction.
- Not counting parity in the endgame. Being forced into the last open region first often means handing your opponent the final say.
- Treating every move like it should flip the most discs. The move that flips the fewest is frequently stronger if it protects a corner or edge.
Frequently Asked Questions
What is the objective of Reversi?
To have the most discs of your color on the board when the game ends โ either the board fills up or neither player has a legal move left.
Why is having more discs in the middle of the game not necessarily good?
Discs in the open middle can still be flipped by later moves. A large early lead is often unstable, while a smaller position built around corners and edges tends to hold up.
Why are corners so important in Reversi?
A disc in a corner can never be flipped, since no line can trap it from both sides. Corners anchor stable discs along their edges, making them the most valuable squares on the board.
What are X-squares and C-squares?
The squares diagonally and directly adjacent to each corner. Playing on them before the corner is settled frequently gives your opponent the move they need to claim it.
What happens if I have no legal move?
Your turn is skipped and passes back to your opponent. If neither player has a legal move, or the board is full, the game ends immediately.
Is Reversi the same game as Othello?
Othello is a trademarked commercial version of the same game, with identical rules โ starting position, flipping mechanic, and win condition are all the same.
Related Guides
- A Beginner's Guide to Puzzle Games โ habits like planning ahead that carry over into Reversi.
- Best Puzzle Games โ see where Reversi fits alongside the site's puzzle and strategy lineup.
- How to Play Connect Four โ another two-player game built around reading threats ahead.
- Play Tic-Tac-Toe โ a smaller, faster strategy game built around forced moves and forks.