Friends , enemies , and family.
You play as a big daddy , yes the one you used to fight , someone has separated you from your little sister and you are going to get her back , but Lamb tries her best not to let you , and this when Sinclair comes for the help , he knows Rapture very well , also he had his issues with Lamb himself.
You must fight your way while you are looking for your little sister, and face lamb's surprises, enemies ambushes, and weird moments, you will also get to interact with elements like hacking, puzzles, recording moments!! And other stuff.
The experience is great, if you enjoyed the great first Bioshock I am sure you will like this one too, a must play game.