GameInformer subscribers have leaked the first details of highly anticipated sequel BioShock 2, including the revelation that co-op will be available, and that there will be NO Big Daddies at all. Strap yourself in for full details, and be aware that spoilers lie ahead.

BioShock 2 tells the story of a private investigator named Jack Abbott, whose daughter is kidnapped by the "Big Sister" character as shown on GameInformer's cover. Abbott pursues the creature by boat and confronts her, but is knocked unconscious and awakes in a certain famous underwater city, which is in even worse shape than it was before, thanks to seven years of ruination between this game and the last.

Things go from bad to worse when a Soviet submarine uncovers Rapture and gets introduced to ADAM -- the precious genetic resource of the first game -- and plan to use it against the Americans in the ensuing Cold War. Jack's forced to defend Rapture and safeguard ADAM from the nefarious Commies.

Hit the jump for more details.

Russian enemies are said to be far more intelligent than Splicers were, able to use cover and flank players rather than simply running headlong with wrenches in their hands.

There will be a selection of new environments that were unseen in the previous game, including a zoo with a collection of spliced up animals, including a mutated rhino and a giant squid that provides "an epic underwater boss fight." Other enemies include spliced dogs and bipedal robots which Jack will be able to hack for his own use.

As far as Plasmids go, we have two new ones confirmed. One slows down time for a few seconds, and another, far more intriguing one, is telepathy. Telepathy allows you to listen to the thoughts of NPCs, which can be useful for getting information like keypad combinations and the like.

Finally, the game will allow for co-op. That's all we know on multiplayer so far.

What do you think? Do these early details sound good to you? I'm a bit worried, despite my crossed fingers. The plot details sound like they could work, but I'll need to find out more before getting excited. Spliced dogs and rhinos also have potential to be incredibly silly as opposed to scary, so there's that. Co-op and the lack of Big Daddies are two pretty huge things that could dramatically alter the way this game goes.

In short, I don't know what to think. Somebody tell me.