Opening Search

The opening search field lets you find games by their opening position or move sequence. The dropdown next to the input controls how the matching is performed.

Search Modes
ModeDescription
Position (default)Finds all games that passed through a given board position during the first 20 moves. The match considers which pieces are on the board, how they are connected, and whose turn it is — but not which piece moved last. Two different move orders that reach the same layout with the same player to move will match.
HistoryMatches games whose move history begins with the exact sequence of moves you entered. The moves must appear in the same order, at the same positions in the game. This is a prefix match on the canonical UHP history.
Input Formats (Position mode)

Position mode accepts two kinds of input:

  • UHP moves — a semicolon-separated sequence of moves in standard notation. The moves are replayed and the resulting board position is used to find matching games.
    Example: wL; bL wL-; wM -wL
  • HOP notation — a HOP string describing the position directly. If the input contains a comma it is treated as HOP. Any ! marker (last-moved piece) in the input is stripped automatically since position search ignores which piece moved last.
    Example: Ll-M+q,w
Input Format (History mode)

History mode accepts moves in standard notation. Moves are separated by semicolons. Notation is case-insensitive and whitespace-tolerant.

Coverage

Only the first 20 moves of each game are indexed for position search. Positions beyond move 20 are not searchable.

Examples

Suppose you enter wL; bL wL-; wM -wL:

  • Position finds any game that at some point (within the first 20 moves) had the same three-piece arrangement with white to move, regardless of move order.
  • History finds games that started with those exact three moves (white ladybug, then black ladybug to the right of white ladybug, then white mosquito to the left of white ladybug).
Position Encoding

Position matching uses HOP notation internally. HOP describes the shape of the position without reference to absolute coordinates, so rotated or shifted versions of the same arrangement are treated as identical. The last-moved marker (!) is excluded from the stored positions, meaning two games that reach the same layout via different last moves will match.