BioShock 2 is a great game. Masterfully crafted by 2K Marin, it retains the atmosphere that made BioShock such an innovative and stunning exploration in 2007 while also telling a story that adds to the lore of Rapture, the city under the sea in which BioShock takes place.
BioShock 2 tells the story of Subject Delta, the original Big Daddy. Forced to kill himself at the beginning of the story, he awakes from his wounds ten years later, still alive though uncertain about his past. As Subject Delta you have to explore Rapture's crumbling ruins to try and find your daughter, Eleanor.