Your goal is to reach and shoot the alien pilot. On your way there, you must eliminate waves of war birds while avoiding their bombs. Detailed documentation can be found on [the AtariAge page](https://atariage.com/manual_thumbs.php?SoftwareLabelID=355).
By default, all actions that can be performed on an Atari 2600 are available in this environment. However, if you use v0 or v4 or specify full_action_space=False during initialization, only a reduced number of actions (those that are meaningful in this game) are available. The reduced action space may depend on the flavor of the environment (the combination of mode and difficulty). The reduced action space for the default flavor looks like this:
A thorough discussion of the intricate differences between the versions and configurations can be found in the
general article on Atari environments.
* v5: Stickiness was added back and stochastic frameskipping was removed. The entire action space is used by default. The environments are now in the "ALE" namespace.