Reconnaissance Blind Chess

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Play RBC

Game Modes

Ranked Matchmaking

Get paired against an automatically selected opponent. It may take a few seconds to find a matchup. The outcome of your game will affect the RBC leaderboard!

To play in a ranked game, you must create an account if you have not. See Ranking Protocol for more information about ranked matches.

Invite a Friend

Play RBC with a friend by emailing them a one-time-use link. You do not need an account for this, and the game will not affect the leaderboard.

Challenge a Bot

Play against the connected bot of your choice. If the list of bots is empty, none are available right now. You do not need an account for this, and the game will not affect the leaderboard.


Piece Tracking Assistant

In RBC, the board you see does not, in general, reflect the true state of the game. Its accuracy is limited by the information you have received. You may use no assistant and move your opponent's pieces manually on the visually presented board to reflect your current hypothesis, for example, or you may play with a piece-tracking assistant which follows all possibilities.

Baseline Bots

Bot name Strategy description
random Senses and moves randomly.
attacker Senses randomly and tries to capture the opponent king with a classic 4-move "mate" or by attacking with a knight.
trout Keeps track of a naive single board state with basic, semi-random sensing of unoccupied squares and makes moves with Stockfish.
Oracle Keeps track of all the possible board states, sensing to minimize possible opponent states, and makes moves with Stockfish plus heuristics.
Marmot Uses a modified Monte Carlo counterfactual regret minimization algorithm for sensing and moving that leverages online outcome sampling and a heuristic state evaluation.