The player will take the role of the first Big Daddy ever created in Rapture, who possesses superior speed and intelligence(he is able to think for himself) than subsequent Big Daddies, though he lacks some of their strength.He has seemingly survived the events of the first game. As such, the player will be able to use the Big Daddy's drill and rivet gun as weapons, though the drill will overheat if used continuously. The Rivet gun will have several types of ammo, similar to the first game. Alternatively, in contrast to other Big Daddies, the player may also use plasmids, while "upgrade trees" will provide unique ways to upgrade them. A new feature added is the ability to dual-wield plasmids and weapons at the same time. Further Big Daddy abilities found in the first game, such as performing a shoulder dash, will also be an option. The player will also be able to step outside Rapture into the ocean due to the diving suit they wear. Here the player can explore the ocean floor, recover from fights, marvel at the city from the outside and even pick up the special sea slugs at the ocean floor to gain more ADAM. These sea slugs are gene-modified so they create ADAM. The slugs were the original idea instead of Little Sisters in the first BioShock. The Big Sister also appears to be a very serious threat to the player. When a certain number of Big Daddies are killed she will attack. Unlike the Big Daddies, she is lightning quick and arguably more powerful, able to extract ADAM from her enemies through a harvesting needle, straight into her bloodstream, which fuels "telekinetic abilities beyond anything previously thought possible"