Reversi Openings
Reversi has far fewer opening variations than chess, but your habits in the first ten moves decide your midgame mobility. This guide covers Black's first move, White's three standard replies and the principles that keep you out of trouble.
The first move: four squares, one move
Black has four legal first moves: d3, c4, f5 and e6. Because the board is symmetric they are the same move rotated or mirrored, so none is better than the others. By convention f5 is treated as the standard first move, and opening names are given from there.
White's three replies
After 1. f5, White has three legal moves: d6, f6 and f4. Each one defines one of the three main openings: perpendicular, diagonal and parallel.
The perpendicular opening: f5, d6
White plays d6, at a right angle to Black's f5. This is one of the most common and richest openings; both sides keep good mobility.
The diagonal opening: f5, f6
White plays f6, next to f5, and flips e5 along the diagonal. Also a mainstream opening; positions tend to be tangled and reward careful mobility counting. Note that White flips e5 on the diagonal, not the adjacent f5: only outflanked discs flip.
The parallel opening: f5, f4
White plays f4, parallel to f5. This opening is generally considered slightly worse for White because Black gets the better mobility, so it is rare in strong play. For a beginner it is enough to recognise it and not panic when an opponent plays it.
Five opening principles
- Stay central. For the first ten moves keep to the central 4×4 to 6×6 area. Do not rush to the edges or corners.
- Flip little. One or two discs per move keeps your group compact with few frontier discs.
- Avoid X-squares and C-squares. Playing next to a corner this early is practically giving it away.
- Count your opponent's moves. After each move ask how many legal moves they have. Fewer is better.
- Do not grab edges early. Edge discs with gaps are easy for the opponent to exploit.
The reasoning behind each of these is in the strategy guide.
How to practise openings
The fastest way to learn is to open a game against the Advanced or Hard AI in ReversiAI, play the same opening ten times, and watch how your mobility changes by move 15. When a position is unclear, press the best-move hint to see the recommended move, then undo and try it yourself.
Frequently asked questions
What is the best first move in Reversi?
All four legal first moves (d3, c4, f5, e6) are equivalent by symmetry. f5 is the conventional choice.
How many openings are there in Reversi?
Three main families, named by White's reply to f5: perpendicular (d6), diagonal (f6) and parallel (f4). The first two are mainstream.
Why is the parallel opening rare?
It is generally considered to give Black better mobility, so strong players prefer the perpendicular or diagonal opening as White.
Should I take edges in the opening?
No. Early edge discs often leave gaps that the opponent can exploit. Stay compact in the centre and keep your mobility.