Prince of Persia

The E3 walkthrough is essentially one long, multi-part boss battle broken up by platforming sections. The Prince swings from poles, runs up walls and bounds around with all the grace and agility you'd expect. It contains all the familiar traits of the genre, with Elika's abilities finessing the experience with depth and variety.

The 'Elika button' - triangle on PS3, which the game's being demoed on - is the one-stop shop for all your companion-related needs. It's all contextual: bugger up a jump and she'll sweep to the rescue; press it when you're just standing around and you can have a nice old chin-wag. This is used to convey extra background on the story and characters for those who are about such things, in a similar manner to the function performed by the tapes in BioShock.

Elika's magical abilities are upgradeable. The two on display in the demo are a compass ability, which sees her shoot white light from her hands to show the Prince which way to go, and a rebound move, which enables jumps over vast and otherwise impossible distances, utilising specific areas marked on the environment.

You can upgrade Elika's powers in any order you like, and which powers you have will determine to a point where you can go. We're told progression will be "Zelda-like", where Elika's abilities will provide access to previously inaccessible areas as, say, the hookshot would in Nintendo's series.

But the main guy isn't without a few new tricks of his own. There's a slide move, for one, but more significant is the Grip Fall, where the Prince digs his gauntlet into a wall while falling to slow his descent and allow him to spring off elsewhere.

It's all very slick, but what really gets us going are the boss encounters. Here, the action becomes magnificently dramatic, aided by brilliant use of the camera, which dives in and out, seeking to give the most striking view of the battle. Here also, the glorious, pulsating beauty of the visuals is suddenly apparent - the giant beast the Prince is fighting swells magnificently with The Corruption, and the fluidity of movement is a joy to behold.

Each face button offers a different type of attack: sword, glove, jump and, of course, Elika. Since this is early on in the game, the bouts frequently pause to flash up single-line tutorials on how to block, counter-attack, escape grab attacks and so on. At one point the Prince and his massive foe lock weapons, requiring frantic button-bashing to avoid buckling under the pressure. The camera zooms right in for an extreme close-up, ramping up the tension. It looks awesome - as do the stunning vertical shots employed to show-off a meaty juggling combo as Elika wades in with her contribution.

Each time the enemy is overcome, it bounds off further into the level as the game switches back to platforming as you make your pursuit. Beaten for the final time, the duo gain access to the Fertile Ground, an area in which Elika's magical powers are spectacularly harnessed to force out The Corruption. Newly healed, the environment is transformed, with vegetation bursting from the ground and clouds breaking to reveal blue skies.

For all its current class, the code is clearly unfinished at this stage, with numerous bugs evident and a frame-rate that plunges dramatically in places. All things we'd expect to be taken care of before release, but one that does make us question the viability of a pre-Christmas release.

"At least in my conversations it's got to be out for Christmas," insists Mattes. "We want the Christmas market, we want a one year stagger with Assassin's Creed." But for a game of such importance to the company, clearly it won't be rushed out in time to be squeezed into little Billy's stocking.

"Obviously we're not going to release the game if the quality's not there, that's for sure," Mattes adds. But our goal is to make sure the quality is there in time." Given the extra time afforded to other Ubi titles (or, in Haze's case, massive waste of time), we won't fall off our chair if this one slips into 2009; but we are crossing everything that it does hit its date.

Either way, there won't be a demo. "Not planned," says Mattes. "Not necessarily convinced we need to; and doing demos of open world games is a technical challenge. It's a brand that has some history, some built in fan-base and we can benefit a little bit from that. There's just so many awful demos: you're doing your game a disservice by putting in players hands before it's ready. Nobody wants that."

What we see in our brief teaser is, according to Mattes, a "microscopic fraction" of the game's content (indeed, a sneaky glance at one of the monitors on the team's floor reveals a stunning-looking Mario Galaxy-style stage with the Prince scampering all over massive, rotating platforms in the sky).