Guide
Three-player chess, explained
A guide to 3Chess: the rules, why the game works the way it does, and how it compares to every chess variant that came before it.
3Chess is a three-player chess game on a 127-cell hexagonal board. It keeps the pieces and the patience of regular chess. The third player changes everything else.
Alliances shift mid-game. A win is no longer mate-or-be-mated. The board itself has to be symmetric in a way a square never could be. This guide covers all of it.
New here? Start with how to play, or just open the board and learn by doing. Every legal move is highlighted, so you can feel the geometry before you read about it.
Start here
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How to play
The complete ruleset: the 127-cell hexagonal board, the three symmetric territories, how every piece moves, check and checkmate, elimination, territory scoring, and the 20-move rule.
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What three-player chess is
Why three players, why a hexagon, and how 3Chess solves the kingmaker problem that has made every previous attempt at 3-player chess feel arbitrary.
Go deeper
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Chess variants
A quick orientation to the main families — three-player, hexagonal, Bughouse, Crazyhouse, Chess960 — and where 3Chess sits among them.
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Glossary
Canonical definitions of the terms 3Chess uses: cascading checkmate, kingmaker problem, territory scoring, the 127-cell hex board, 120° symmetry, paranoid search, PL-Elo Exact, and the axiom system.
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Articles
Design essays, research, and tech notes: the kingmaker problem, the 120°-symmetric board, the hex chess renderer in Rust + WebGPU, the three-way AI.
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About Round Online
The independent studio behind 3Chess — what we make, how we approach design, and how to reach us.