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What is Pie Chess?

Pie Chess is a new chess variant in which one player sets up a custom position, and the other player decides which colour to play or to take draw odds.

The name "Pie Chess" is an allusion to the pie rule, where someone cuts a pie into two slices and lets the other person choose which slice they want, incentivizing cutting it fairly. This rule is used in other games such as Hex to make the first move more fair. Similarly, in Pie Chess, the player who sets up the position must create a balanced position, knowing that their opponent will get to choose the more advantageous side.

How It Works

  1. Position Setup: One player (randomly selected) sets up a custom chess position, including whose turn it is. The only constraint is that there must be at least one legal move available.
  2. The Choice: The other player must choose either:
    • "Win" - and select which color they want to play
    • "Draw" - in which case the first player chooses the color
  3. Draw Odds: The player who did NOT choose "Win" gets draw odds (they win if the game ends in a draw). If "Draw" was chosen, the player who chose "Draw" gets the draw odds.
  4. Gameplay: The game proceeds as normal chess, with the clock starting after the position is set up and the choice is made. The second player receives a time bonus.

See this article for more.

🖥️ Play vs Computer 👥 Play vs Human

📊 ELO Rating System

Pie Chess uses a Maximum Likelihood ELO rating system to calculate player rankings. Your rating starts at 1500 (the default beginning rating) if you have no games played.

How it works: The system uses Bayesian inference to determine optimal rating ranges that best explain the observed match outcomes. Instead of giving a single point estimate, the system calculates rating ranges that reflect confidence based on available data:

  • Narrower ranges indicate more confidence (more comparison data)
  • Wider ranges indicate more uncertainty (less comparison data)
  • Ratings are calculated using the standard ELO formula: P(x beats y) = 1 / (1 + 10^((y - x) / 400))

Note on Cheating Detection: While we are not currently implementing automated cheating detection, we monitor game patterns and may investigate suspicious activity. Fair play is essential for maintaining accurate ratings.

Tournaments: In tournament mode, all players' ratings are reset to 1500 at the start. Ratings are then calculated after a set number of games that participants play.

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