Fallout 2 is a role-playing open world video game. The player is free to move at will until they enter into combat. Combat gives them a number of action points to move, fire, check their equipment, reload and the like. When a player uses up all of their action points, they end their turn and enemies start theirs. If the player survives unharmed, he or she has their action points restored. Injuries and poisons can reduce the number of action points available both in a single term and semi-permanently until combat ends and the player can be treated. Combat and completion of jobs or quests rewards the player with experience points with which they can level up their characters and apply beneficial perks to become more suited to the dangerous post-apocalyptic world. General gameplay consists of traveling and interacting with local inhabitants and organizations to complete goals and aid or inhibit the NPCs. The player's actions dictate what future story or gameplay opportunities are available. Mature themes such as alcohol consumption, drug usage and sex are present.
Organized crime, prostitution and slavery are major elements of the setting. Character creation is based on the SPECIAL role-playing system.
In 2241, the primitive Arroyo suffers the worst drought on record. Faced with the calamity, the village elder asks the direct descendant of the Vault Dweller, referred to as the Chosen One, to perform the quest of retrieving a Garden of Eden Creation Kit (GECK) for Arroyo. The GECK is a device that can create thriving communities out of the post-apocalyptic wasteland. The player, assuming the role of the Chosen One, is given nothing more than the Vault Dweller's jumpsuit, a RobCo PIPBoy 2000 handheld device, a Vault 13 water flask, a spear and some cash to start on his mission.