Ten years have passed since the events in BioShock. The underwater-city Rapture has further deteriorated, with water breaking in everywhere and whole sections flooded by water. But as bad as the situation is, the city still isn’t empty. After Andrew Ryan’s death, his long adversary, the psychiatrist Dr. Sophia Lamb took over the helm – embracing her own cult, making the mutated splicers that roam the city her worshippers. In the middle is Delta, the first of the protectors of the Little Sisters better known as Big Daddies. Eternally bonded to one and only one Little Sister called Eleanor, daughter of Sophia Lamb, he’s damned to search the city and find her or die trying.
The player slips into the mighty boots of Delta, making his way in a typical first-person-shooter-style through the city of Rapture to find and confront Dr. Sophia Lamb, who holds Eleanor against her will. The switch of perspective, in the first game the player was a normal human, also brings with it a few changes in gameplay. The most important being, that the player can now use both one of the eleven available plasmids and one of the several different weapons at the same time, allowing him to burn enemies while pumping them full of bullets. Other plasmids include “Winter Blast” which freezes an enemy or “Scout” which allows the player to leave his body and look around unnoticed. The weapons on the hand range from the famous Big-Daddy-Drill over a powerful double-barrel-shotgun to a grenade launcher.
As in the first game, both weapons and plasmids are upgradeable. While the weapons just require the player to find a special workstation, upgrades for plasmids and tonics (granting passive effects) are bought at special vending machines called “Gatherer’s Garden” with the rare substance called “Adam”. As in the first game, the Little Sisters roaming the levels are the key to getting access to Adam. But since the player himself is a Big Daddy, the process is a bit different this time around. While the player still needs to kill the accompanying Big Daddy to get access to the Little Sister, he can choose to adopt it afterwards instead of just harvesting it. The Little Sister will then sit on his shoulder and look for Adam-infused bodies in the level to harvest them.
Setting down a Little Sister to harvest a body will unleash hell as every splicer in the level will try to kill her, requiring the player to protect the little girl from harm until its finished collecting. Once a Little Sister has harvested two bodies, the player can again either harvest her himself, or free her. Either action grants him more or less Adam and at the same time may alert a Big Sister. As opposed to the Big Daddies, they are nimble, fast and very deadly.
Another important change is the new hacking-mini-game which is the same in all versions now and requires the player to hit the green or blue spaces on a gauge with a constantly spinning needle. If he doesn’t hit the right field, he either gets a electro-shock or will sound the alarm. A successful hack on the other will lower the prices at vending machines or turn turrets over to the player’s side. The new mini-game also allows the player to fight and walk around while hacking as well as hacking from a distance thanks to the arrows shot by the hacking-tool.
BioShock 2 features multiplayer for up to 10 players which was developed independently from the single player by a different developer and tells the story before the first game. By gaining ranks for kills and winning matches, the player unlocks access to additional radio messages advancing the story behind the civil war that raged in the city between the Splicers and Andrew Ryan’s security force. The available multiplayer-mode include Deathmatch, Team-Deathmatch, Capture and Hold, Capture the Sister and Adam Grab. The latter requires the players to collect and protect the sole Little Sister in the level in order to gain points. Capture the Sister on the other hand puts two teams against each other with one team trying to bring the Little Sister to a vent and the other trying to prevent that. Each mode also features the possibility of one player slipping into the role of a Big Daddy.