Chess Pressure

A web application that visualizes pressure maps on a chess board -- showing which squares are controlled by white vs. black across every move of a game.

What is "pressure"?

For each square on the board, pressure is the net number of pieces attacking it. Positive values mean white controls the square; negative means black does. Two modes are available:

• Unweighted -- each attacking piece contributes +1 or -1.
• Weighted -- each attacking piece contributes its material value (pawn=1, knight/bishop=3, rook=5, queen=9, king=1).

Features

• Step through famous built-in games move by move and watch the pressure heatmap evolve.
• Upload your own PGN to analyze any game.
• Make moves from any position and see legal moves + pressure updates in real time.
• FastAPI backend with a lightweight static frontend.

Built-in Games

Game	Year	White	Black
The Immortal Game	1851	Anderssen	Kieseritzky
The Opera Game	1858	Morphy	Duke of Brunswick & Count Isouard
Fischer vs Spassky, Game 6	1972	Fischer	Spassky
Xie Jun vs Chiburdanidze, WCC	1991	Xie Jun	Chiburdanidze
Kasparov vs Deep Blue, Game 2	1997	Deep Blue	Kasparov
Polgar vs Anand	1999	Polgar	Anand
Polgar vs Kasparov	2002	Polgar	Kasparov
Carlsen vs Nakamura	2010	Carlsen	Nakamura
Hou Yifan vs Caruana	2017	Hou Yifan	Caruana
Ju Wenjun vs Lei Tingjie, WCC G12	2023	Ju Wenjun	Lei Tingjie

Quickstart

uv run chess-pressure

The app starts on http://localhost:8888.

API

Method	Endpoint	Description
GET	/api/games	List built-in games
GET	/api/games/{id}	Load a built-in game (headers, moves, pressure frames)
POST	/api/parse	Parse a PGN string ({"pgn": "..."})
GET	/api/legal?fen=...	Get legal moves for a FEN position
POST	/api/move	Make a move ({"fen": "...", "uci": "e2e4"})

Project Structure

src/chess_pressure/
  __init__.py
  app.py       # FastAPI routes and static file serving
  engine.py    # Pressure computation, PGN parsing, move logic
  games.py     # Built-in famous games (PGN data)
  static/      # Frontend assets (HTML, JS, CSS, piece images)

License

MIT