BioShock 2 is set in the fictional city of Rapture, hidden from the rest of the world underwater, who was built to escape the tyranny of governments. BioShock 2 is presented as a first person shooter, where the player taking on the role of Subject Delta, a prototype for 8 years after the events of the first game. As in BioShock, the player explores Rapture and fights off splicers, the remaining psychotic human population of the undersea city, using a combination of the environment, weapons, plasmids, and tonics. Plasmids and tonics are special genetic-reencoding liquids that grant the user active or passive abilities, respectively, and include many of those introduced in BioShock as well as new ones.
As the player explores Rapture, he will collect ammo, health, recovery items, money and EVE (a liquid used to power plasmid use). Money can be used to purchase more items at vending machines scattered around the city.