BioShock Infinite

Of course guns only form the blueprint of BioShock's combat, and Infinite is no different. Vigors like the aforementioned Bucking Broncos allow you to launch enemies and objects into the air - useful for flushing out foes behind cover - and the previously revealed Murder of Crows sends a flock of birds to distract enemies. These add a little spice, but the bigger change is Elizabeth's ability to manipulate "tears" in the environment. The world is littered with various translucent objects that Elizabeth can will into existence. A cart creates cover, a turret provides firepower, and a rail car on a Sky-Line turns into a moving train that pushes enemies off ledges. She can only activate so many tears at a time, though, so you'll have to choose wisely.

Possibly the biggest innovation are the Sky-Lines, a system of rails connecting the various floating islands. Only glimpsed sparingly in the debut trailer, one would be forgiven for thinking they were nothing more than a flashy method of moving from one linear set-piece to another. This couldn't be further from the truth. Sky-Lines are everywhere and provide plenty of opportunities to zip about more open battles.

Hopping from one rail to another is a major component of the game, transforming it almost into a platformer at times. It's hard to gauge how intuitive this will be, but director of product development Timothy Gerritsen boasts that a lot of work has gone into ensuring this is user friendly. Your aiming reticule will dictate when it's safe to jump and you can fine-tune your trajectory mid-air. Riding the rails is exhilarating with swift swooping movements and rickety creaks giving a strong roller coaster vibe.

Compared to Rapture's claustrophobic interiors, BioShock Infinite contains less fluid, but more fluidity. Sky-Lines can be used by foes as well, so you have to keep moving. While not shown in the demo, Gerritsen says they've swapped out BioShock's cumbersome weapon wheel for something more akin to Uncharted where you can only hold a couple guns at a time. This new limitation would be frustrating if Elizabeth couldn't take care of herself, but Levine assures us there will be no escort missions and Elizabeth can't die due to neglect. In fact, she'll even fight alongside you.

The demo ends with the songbird's second appearance. Tossing you through a building you awaken to Elizabeth standing before you, defiantly using herself as a human shield. "I'm sorry," she cries. "I never should have left. Take me home. Please!" The songbird whisks her off as she stares longingly back as you reach for each other in vain.

There are still plenty of unanswered questions. What do the founders want with Elizabeth? Why do the Vox Populi want her dead? What's in the tower? Why does she have super powers? What is she capable of? Where were we when Elizabeth opened the tear? Who's the mysterious figure that wants her back in New York? And what secret is Booker hiding in his past?

Based on the demo, Irrational has certainly upped the ante in terms of storytelling. All this happened in real-time without an audio diary or pandering piece of exposition in sight. In BioShock "you arrived in Rapture as an archaeologist," says Levine. "When you arrive in Columbia things are very much still in motion, and you freeing Elizabeth puts the torch to everything."

BioShock Infinite maintains the peculiar mix of unique historical settings and science fiction that made the first game such a rousing success. Touching character moments, tantalising foreshadowing, and thrilling set-pieces are all noticeable improvements upon its predecessor if the demos are any indication. Following up one of the most highly acclaimed games of the generation is no small feat, but as DeWitt said, "After what just happened, you really want to take bets on what's possible?"