---
id: ale-py
version: "0.12.0"
license: GPL-2.0-only
license_treatment: copyleft
maintenance: active
---

# ale-py — The Arcade Learning Environment (ALE) - a platform for AI research.

License: copyleft · Maintenance: active · Downloads: 298.6K/mo

## What it is and what it does

ale-py is a Python wrapper around the Stella Atari 2600 emulator, designed to provide a research-grade platform for developing and benchmarking reinforcement learning agents. It decouples emulation from rendering and sound, enabling fast headless training while also supporting visual output when needed. The package includes Atari ROMs, automatic game-over detection, and score extraction for over 100 games, making it a turnkey environment for RL research without requiring separate ROM management.

The package integrates natively with Gymnasium (the maintained successor to OpenAI Gym), so you can use it either through ale-py's direct ALEInterface API or through Gymnasium's standard environment interface. It also provides a C++-based vectorizer for parallel environment execution and WebAssembly support for browser-based experiments. Runtime dependencies are minimal: only numpy and typing-extensions.

Use it for:

- Train deep reinforcement learning agents on Atari games as a standard RL benchmark.
- Benchmark policy gradient or Q-learning algorithms against a large suite of games.
- Develop and test game-playing agents with automatic score tracking and episode termination.
- Run vectorized parallel environments for faster training of multiple Atari game instances.
- Create interactive browser-based RL demos or educational tools via WebAssembly.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

ale-py provides a Python interface to the Atari 2600 emulator Stella, allowing you to develop and test reinforcement learning agents on classic Atari games with automatic score extraction and game-over detection.

Yes, with conditions. ale-py is actively maintained, widely used in RL research, and has no known vulnerabilities. Install it if you are developing RL agents and need a standard Atari benchmark environment. Be aware of the GPL-2.0-only copyleft license if you plan proprietary use, and ensure your Python version is 3.10 or later (free-threaded CPython is not supported).

## Install

pip install ale-py
uv add ale-py
poetry add ale-py

## Installing ale-py

Before you install: Medium install friction due to compiled wheels for multiple Python versions and platforms; however, prebuilt wheels are available for modern Python (3.10–3.14) on macOS, Linux, and Windows, reducing build complexity. Active maintenance with a recent release.

License in practice: GPL-2.0-only is a copyleft license; any derivative work or modified version must also be distributed under GPL-2.0-only. This may restrict commercial or proprietary use without careful licensing review.

Quickstart:

pip install ale-py

from ale_py import ALEInterface, roms

ale = ALEInterface()
ale.loadROM(roms.get_rom_path("breakout"))
ale.reset_game()
reward = ale.act(0)
screen_obs = ale.getScreenRGB()

Requires Python 3.10 or later; free-threaded CPython (e.g., python3.14t) is not supported due to OpenCV wheel compatibility.

Verify before relying:

- Whether the included Atari ROMs are legally licensed for your intended use.
- Performance characteristics and typical episode length for different Atari games.
- Exact number of supported Atari 2600 games beyond the stated '100+' threshold.

## Package facts

- License: GPL-2.0-only (copyleft)
- Python support: supports_current
- Install friction: medium
- Maintenance: active
- Downloads: 298.6K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

atari 2600 emulator python, reinforcement learning environment, arcade learning environment, atari game agent development, ale-py gymnasium integration, atari rl benchmark, ale interface python, reinforcement-learning, atari-benchmark, emulation

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