Thanks Sluggo.
Heh, just realized that there are probably plenty of people browsing this off topic section who have never played Bioshock, or even know what a Big Daddy looks like, so here is a picture of one from the actual game for comparison.
To give them a little background, they are the guardians of creepy little genetically altered little girls known as "little sisters" in the brilliantly rendered and depicted utopia turned distopia of Rapture. In the game the Big Daddys (lovingly called "Mr. Bubbles" or "Mr. B" for short by the little sisters) won't mess with you until you mess with them or a little sister they are escorting.
The little sister's job is to harvest ADAM, which is a bit more complicated to explain, in short it has to do with genetic manipulation and drugs, which ran rampant in the under water utopia the game takes place in. In Rapture, doctors were free to experiment with all sorts of questionable things in the name of enlightenment and human greatness, which is what the city of Rapture is all about. Ultimately, the citizens constantly using more and more of these drugs to manipulate and improve their bodies caused the minor side effect of gradual insanity.
The little sisters harvest the ADAM out of dead people, and the junkies that liter the place want the ADAM so they can get more powerful genetic manipulations, which is why they need a stout guardian. Once you kill a Big Daddy, you can choose to rescue or harvest the little sister, rescuing her results in a small reward of ADAM, and then she scurries away, now a fairly normal looking little girl because he body is free of ADAM. Choose to harvest her, and she turns into a limp dead slug of a thing, and you get a whole crap load of ADAM. The game has slight alternative endings depending on which option you choose the most.
In the trailer for Bioshock 2, we see the image of a young woman (which we can assume to be a grown up little sister) holding the doll I posted pictures of in my first post.
In other words ignore all this weird stuff I am talking about, and my silly looking rag doll, and play this game. It is one of those rare gems of a game that only comes along once every few years. Sure, it is just another silly first person shooter that really doesn't do anything new to speak of, but its backstory is so indepth it will suck you in. Another plus is that you only have to look into the backstory as dee as you feel like. If you only want to blow things up and kill people, then you can. But if you want to really take the time to find out exactly what Rapture was and what kinds of things went on there to turn it from an idealogically perfect capitalist society into a dark, damp, and bloody junkie ridden hive of anarchy, then you are free to do so.