Think you can outplay the AI?

Meet the challengers

Each challenger has a signature style — pick one that matches your mood.

Random Randy

“Let's see what happens!”

Randy plays without a plan, a preference, or a clue. Every move is chosen in the moment, free from strategy or regret. There is a strange freedom in his chaos — but no consistency to save him.

The Collector

"More pieces means I'm winning... right?"

The Collector loves the sound of flipping discs. Big swings, dramatic turns, and immediate gratification — what could go wrong?

Endgame Monster

"Everything before this was warm-up."

Sloppy early, dangerous late. Endgame Monster comes alive when the board empties and every move is fate. Give him time, and he will find the perfect line — relentlessly.

The Gambler

"Winners are those who dare to risk it all!"

The Gambler lives for the thrill. Sometimes his instincts are brilliant. Sometimes they're catastrophic.

Mobility Purist

"Options are everything."

Mobility Purist plays for freedom above all else, hoarding moves like treasure. The board stays open, lively, and flexible.

The Positionist

"This position feels right."

The Positionist shapes the board with confidence and care. Openings are meticulously calculated, midgame play is smooth and purposeful. He cares about beauty, not winning and losing.

The Turtle

"If I don't move, I can't lose."

The Turtle plays like the board is hostile territory. Every move is cautious, every piece tucked safely away. He survives by refusing to engage.

The Rock

"I will not blink."

The Rock is immovable, disciplined, and unyielding. She avoids danger even when it's necessary, preferring safety over initiative.

Opening Scholar

"According to the book..."

Opening Scholar knows theory cold. Every early move is polished, practiced, and precise.

The Veteran

"I've been here longer than you imagine..."

Relaxed, balanced, and quietly experienced. The Veteran doesn't rush and doesn't panic. Over long games, however, small lapses creep in — moments where focus drifts.

The Machine

"There is a best move. I will always play it."

The Machine plays Reversi as a solved problem. Every position is evaluated, every move chosen with absolute certainty. It never hesitates, never improvises, and never deviates.

The Elder

“You are not here to win.”

The Elder does not chase perfect moves or dramatic victories. She allows the game to unfold, gently shaping it with patience and restraint. Small advantages are given time to grow. Against her, winning is rare... but the goal is not to win — it is to see the game clearly.

Standing on the shoulders of giants

Reversi Nexus wouldn't exist without the work of these people and communities.

• Logistello by Michael Buro — The pioneering Othello engine that defeated world champion Takeshi Murakami in 1997. Buro's research on ProbCut, pattern-based evaluation, and opening book learning laid the groundwork for modern computer Othello.
• Edax by Richard Delorme — One of the strongest open-source Othello engines, known for its fast bitboard implementation and accurate evaluation. Notably used to verify the results in Takizawa's "Othello is Solved" paper.
• Egaroucid by Takuto Yamana — An outstanding Othello engine whose technical explanations were invaluable for understanding search algorithms and evaluation heuristics. Egaroucid's free training data was also used to help build our opening book.
• Hiroki Takizawa — For the 2023 paper "Othello is Solved" proving the game ends in a draw with perfect play.
• WThor Database — The French Federation of Othello's comprehensive archive of professional tournament games since 1977, used alongside Egaroucid's data for our opening book.
• Robert Gatliff's Opening Catalog — Excellent collection of named Othello openings.
• The Othello/Reversi community — Decades of strategic insights and heuristic development that benefit every new engine.