found this comment left on the vid "I read a developer interview about this so I'll tell you guys what I know.
The game is set 10 years after the original in a half demolished Rapture.
You don't play as Jack. (Obv)
You play as a Big Daddy. The prototype to be precise. Which was a failed experiment as you were way to powerful for the scientists liking. You are faster, stronger and better than all of the other Big Daddys. (And can use plasmids, unlike them.)
You can adopt little sister and use them to harvest adam, but you must look after them.
The main (well I don't know how to put this,) ad guy in the game is a little sister who survived long enough to grow up. Shes the big sister, and is slightly insane. If youve seen the teaser on GT or at the end of the PS3 game, its the girl in that.
She formed herself a suit similar to a Big Daddy's but shes smaller and can manouver much better in it.
Every few Little sisters you adopt, wherever you are she will come and fight you. (Unscripted boss batlles ftw!!!)
I don't know much about how the battles end, but its early days yet.
In this video you see here flood a hall by breaking the glass. As a big Daddy you're in quite a substantial diving suit so you can move around with ease. You can venture out into the seabed if you like in some of the sections.
Now, all I know about weaponry is that you are stuck with a drill all the time and can pick up weapons specifically crafter for the big daddy, and theyre all upgradable.
Being very strong you can hold all weapons in one hand, so you can use plasmids and weapons at the same time."