OpenSpiel: A Framework for Reinforcement Learning in Games

1.6.12 · active · verified Fri Apr 17

OpenSpiel is a collection of environments and algorithms for research in reinforcement learning and search in games. It provides implementations of numerous games (e.g., Chess, Go, Poker, Tic-Tac-Toe) and common algorithms (e.g., MCTS, AlphaZero, CFR). The library is currently at version 1.6.12, with frequent staging releases in preparation for a major 2.0 release. It's developed and maintained by Google DeepMind.

Common errors

```
ModuleNotFoundError: No module named 'pyspiel'
```
cause The `open-spiel` package, or its `pyspiel` sub-module, is not installed or not accessible in the current Python environment.

fix Ensure you have successfully installed OpenSpiel using `pip install open-spiel` and that your environment is correctly activated.
```
RuntimeError: OpenSpiel requires Python version >= 3.11, but found X.Y.
```
cause You are attempting to use OpenSpiel with an unsupported Python version (older than 3.11).

fix Upgrade your Python installation to version 3.11 or later, or use a virtual environment configured with a supported Python version.
```
TypeError: load_game() missing 1 required positional argument: 'game_string'
```
cause The `pyspiel.load_game()` function expects a string argument representing the name of the game to load (e.g., 'tic_tac_toe').

fix Call `pyspiel.load_game()` with the game's identifier as a string, for example: `game = pyspiel.load_game('tic_tac_toe')`.

Warnings

breaking OpenSpiel is currently in a 'staging' phase for version 2.0. Significant breaking changes are expected in the upcoming 2.0 release, for which a full changelog will be made available. Users should be prepared for API shifts.
Fix: Monitor official OpenSpiel GitHub releases and documentation for 2.0 migration guides. Pin your dependency to 1.x if stability is critical.
breaking Support for Python 3.9 was dropped in version 1.6.4. The current version (1.6.12) requires Python 3.11 or newer.
Fix: Ensure your environment uses Python 3.11 or later. Upgrade your Python installation or use a virtual environment with a supported Python version.
gotcha OpenSpiel is a C++ library with Python bindings. While `pip install` usually provides pre-built wheels, building from source (e.g., for custom modifications or specific platforms) can be complex and requires a C++ compiler, CMake, and other development tools.
Fix: For standard usage, prefer `pip install open-spiel`. If custom compilation is required, follow the detailed instructions in the official documentation, ensuring all build dependencies are met.

Install

pip install open-spiel Install with pip

Imports

pyspiel
wrong:
```
import open_spiel
```
correct:
```
import pyspiel
```
The core Python interface is exposed via the 'pyspiel' module, not 'open_spiel'.
load_game
wrong:
```
game = pyspiel.tic_tac_toe()
```
correct:
```
game = pyspiel.load_game('tic_tac_toe')
```
Games are loaded by string name using `pyspiel.load_game()`, not accessed directly as functions.

Quickstart

This quickstart demonstrates how to load a game, create an initial state, apply an action, and check the game's status using the core `pyspiel` module.

import pyspiel

# Load a game by its string identifier
game = pyspiel.load_game("tic_tac_toe")

# Create a new initial state for the game
state = game.new_initial_state()

# Print the initial state
print("Initial state:\n", state)

# Apply a move (e.g., player 0 places 'X' in the center)
# Actions are integer indices, you can get valid actions via state.legal_actions()
state.apply_action(4) # Assuming 4 is a valid action in Tic-Tac-Toe
print("\nState after move:\n", state)

# Check if the game is terminal
if state.is_terminal():
    print("\nGame is over. Returns:", state.returns())

view raw JSON →