Sequels can be tricky. For every one of them that is eagerly awaited by a rabidly loyal fan base, there are any number which can seem completely unnecessary and in some instances prompt a furious outcry from fans of the game that spawned them. This last reaction is what BioShock 2 encountered when it was first announced. Its predecessor, while not without its issues, created a sizeable cult following on the basis of its story, which roped in elements of steampunk, fantasy and the works of Ayn Rand. Set in the sunken dystopia of Rapture, it introduced players to two of the most iconic characters in the medium – the Little Sisters who collected the genetic fuel ADAM, and their lumbering protectors, the Big Daddys.