Reversi Openings — Named Sequences, Theory, and How to Start the Game

Why Openings Exist in Reversi

Reversi openings are possible because every game starts from the same position — four discs placed in the center diagonal (the Othello starting position). Since the board is identical at the start of every game, players can study and memorize the best move sequences for the first 10–20 moves, just like chess opening theory.

This is a direct consequence of the fixed starting position. In classic reversi, where players freely place their first discs, opening theory would be far more complex because the initial position varies.

The First Move: Black’s Opening

Black always moves first. Due to the board’s eightfold symmetry (rotational and reflectional), Black has only one strategically distinct first move. The four legal squares — d3, c4, f5, and e6 — are all equivalent by symmetry.

By convention, most opening databases use d3 as Black’s standard first move. All opening names and sequences below follow this convention.

After Black plays d3, the board looks like this:

• d3: Black (just placed)
• d4: White (starting disc, now flipped to Black by the d3 placement… actually d4 was White, and the outflank flips d4)
• d5: Black (starting disc)
• e4: Black (starting disc)
• e5: White (starting disc)

White now has three strategically distinct responses, which define the three major opening families.

The Three Opening Families

1. Diagonal Opening (d3, c3)

White plays c3 — perpendicular to Black’s d3, creating a diagonal relationship between the new discs.

Character: The most common and balanced opening in reversi. Both players have roughly equal chances. The Diagonal Opening leads to rich midgame positions with many strategic options.

Why it’s popular: It avoids early asymmetries and gives both players room to develop. Most opening theory has been developed from Diagonal positions because they occur so frequently in tournament play.

Best for: All skill levels. If you’re learning openings, start here.

2. Perpendicular Opening (d3, c5)

White plays c5 — creating a perpendicular (right-angle) relationship to Black’s first move.

Character: Leads to asymmetric, tactical positions where both players need to navigate carefully. The Perpendicular Opening often creates more complex midgame situations with sharper play.

Why it’s interesting: The asymmetry means both sides face different challenges. There’s less room for passive or formulaic play — both players need to actively navigate unique positions.

Best for: Intermediate to advanced players who enjoy tactical positions.

3. Parallel Opening (d3, d6)

White plays d6 — directly opposite Black’s d3, creating a parallel relationship.

Character: Rare at high levels because it tends to create cramped, symmetrical positions that favor Black slightly. The Parallel Opening is considered the weakest of the three main options for White.

Why it’s uncommon: The symmetrical nature gives Black an easier game. White often struggles to find active plans. Strong tournament players almost never play the Parallel Opening as White.

Best for: Players who want to avoid theory and play a simpler, if slightly inferior, game as White.

Named Opening Sequences

Within the Diagonal and Perpendicular families, specific move sequences have individual names. Here are the most important:

From the Diagonal Family

From the Perpendicular Family

Less Common Openings

Opening Principles

Regardless of which named opening you play, the same strategic principles apply:

1. Play Centrally

In the first 10 moves, keep your discs in the center. Avoid playing on edges or near corners. Central play gives you maximum flexibility and a compact position.

2. Keep Your Frontier Small

Choose moves that flip the fewest discs — quiet moves that keep your disc count low and your frontier minimal. This builds mobility for the midgame.

3. Avoid X-Squares and C-Squares

This is obvious from strategy basics but worth repeating: in the opening, never play on danger squares. The game just started — giving away a corner in the first 10 moves is catastrophic.

4. Think About Mobility, Not Territory

The opening is not about claiming space. It’s about creating a position where you have many legal moves and your opponent has few. Disc count is irrelevant in the first 15 moves.

5. Don’t Memorize Too Much

For most players, understanding principles matters far more than memorizing sequences. A player who understands mobility and corner strategy will outplay a player who memorizes openings but doesn’t understand why the moves are good.

Opening Books and Databases

Competitive reversi players use opening books — databases of studied positions with evaluated continuations. An opening book might contain:

• The first 20 moves of every major opening
• Evaluations of each position (which player is ahead)
• Specific continuations that avoid known traps
• Transpositions (different move orders that reach the same position)

Opening books are analogous to chess opening databases and are primarily used by:

• Tournament players preparing for specific opponents
• Computer programs that consult a book for the first 20 moves before switching to calculation
• Serious students who want to understand the theoretical status of each opening

For casual and intermediate players, knowing the general character of each opening family is sufficient.

How to Choose Your Opening

If You’re a Beginner

Play whatever legal move looks good and focus on basic strategy. Openings won’t help you until you understand mobility and corner concepts.

If You’re Intermediate

Learn the Diagonal Opening (d3, c3). It’s the most common, most balanced, and has the most publicly available analysis. From there, learn the Rose and Tiger sequences as your primary repertoire.

If You’re Advanced

Develop knowledge of all three families. Use the Perpendicular Opening to create asymmetric situations where your superior calculation can shine. Study specific sequences against opponents you face regularly.

As Black

Black has the first-move advantage and can choose the opening direction. Most Black players who study openings prefer the Diagonal Opening — it maintains the first-move advantage without creating risky asymmetries.

As White

White responds to Black’s choice. Most White players who study openings learn specific responses to the Diagonal Opening (the Rose and Tiger are responses as White). Against less-prepared opponents, the Perpendicular Opening can create problems.

Openings and the Rest of the Game

Opening theory in reversi is less deep than in chess — a typical reversi opening book covers the first 15–20 moves, while chess theory can extend 30+ moves. After the opening:

• Midgame: Apply mobility strategy, maneuver for corners, manage frontiers
• Endgame: Shift to parity and disc counting

The opening sets the table, but the meal is served in the midgame and endgame. A good opening with poor midgame play loses to a mediocre opening with strong positional understanding every time.