Ubisoft will have to forgive me for being a bit sceptical about the 3D graphics in this game. Prior to Avatar, my last experience with 3d graphics was Nanosaur 2 - a pterodactyl-based shooter that came bundled with my iMac. It was a half-decent blaster, but while the stereographic technology worked rather well I still walked away feeling that the whole feature was little more than a gimmick.

So, has Ubisoft changed my opinion on this matter? Not exactly. I'm still not convinced that stereo graphics are about to revolutionise gaming, but on the strength of Avatar I can certainly see how they can add something worthwhile to the overall experience. Avatar is a third-person shooter set within the lush jungles of an alien planet; we've seen this kind of setting time and time again, and yet somehow it seems so much more alive when the scenery seems to have a visible depth. There you are, deep into the middle of a hostile rainforest, and as you turn around all you can see is an endless maze of colourful plant life - much of which is trying to kill you.

Of course, much of this effect is due to the design of Pandora itself. For the last four years Ubisoft has been working with director James Cameron as he builds his long-awaited sci-fi opus. Let's not forget that Jim was the man who brought us the Terminator, the Alien Queen and the Ripley's magnificent power-loader. Cameron and his designers know a thing or two about making cool toys, and it's already clear that both Avatar the Film and Avatar the Game will be packed with eye-catching goodies: lanky blue aliens, hoverships that look like dragonflies, and stompy stompy mech suits.

To be honest this is probably just as well, because only a few of us are ever going to experience this game in all its three dimensional glory. To play Avatar in 3D you'll need an HDTV capable of using a 120 Hz refresh rate in full 1080p, which currently means buying a fairly top-end set. You'll also need an HDMI-equipped console, meaning early generation Xbox 360s aren't up to the job. Ubisoft are quick to assert that funny-specs-o-vision-mode (my term, not theirs) is an entirely optional bonus, a stereographic cherry atop an already-sumptuous adventure cake; That may be true, but there's no denying the fact that if you leave aside the 3D aspect, there's a risk that Avatar could easily be written off as just another Gears of War clone.

On the other hand, most third-person shooters can't stick the words "James Cameron's Avatar" on the front of the box. The success of the film will surely be linked to the success of the game, but if nothing else this will be a shooter backed up by a brilliant concept. In the distant future, humans are attempting to harvest valuable resources from the planet Pandora, which is populated by 10ft tall creatures known as the Na'vi. Since the air on Pandora is toxic, the visiting corporations are forced to rely upon protective gear... until someone hits upon the idea of breeding human-Na'vi hybrids. These genetically engineered half-breeds can then be controlled remotely from a safe location, allowing their "pilots" to walk around the planet as if they were one of the locals.

Aw, don't shoot him! He looks so friendly!

While Ubi's game will tell a different story to its big-screen cousin, the action will focus on the same clash between nature and technology. Throughout the game you'll play as a human marine (think big guns and shooty machines) and as a 10ft tall Na'vi (think clubs, bows and probably a set of panpipes too), but eventually you'll have to make a choice and side with one faction or the other. At Cologne I only had a chance to play a human, on a mission which involved clearing out an area of jungle for an approaching convoy - first in one of those cool hoverships that you've seen in the film's trailer, then on foot.

The initial part of the demo was essentially an excuse to blow up a lot of jungle in a snazzy looking vehicle. While the destruction mechanics weren't as detailed as, say, Red Faction: Guerrilla, the overall effect was rather impressive thanks to the detail of the models and terrain. Again, the 3D graphics really added something in this regard, as they make it easier to pick out tiny details on the ship - like the blades on the vehicle's circular rotors. After a few minutes of wanton destruction, I landed my flying death-copter and tucked into the meat of the demo.

In simple terms, the level involved a jaunt through the jungle shooting everything that moved. While the level itself essentially consisted of several linear paths (as opposed to a single open area), there were plenty of branches in the road that allowed the player to head off to explore optional areas. These in turn lead to additional bonus objectives, of which there were a great many - from assisting fellow soldiers to gathering collectibles and re-activating bits of abandoned machinery. I'm told that many of these objectives had been included for demonstration purposes (i.e. the level wasn't a final draft), but if they're representative of the full game, there should be plenty of distractions from your core missions.

The action gameplay itself took a very familiar form, with run-and-gun controls that felt instantly familiar. Your heroic space marine can dive out of the way of approaching threats, but for once there doesn't seem to be any form of cover system. More controversially, there doesn't appear to be any way to get a zoomed-in view with your weapon of choice. Perhaps this has something to do with the 3D graphics, but it's certainly a notable omission. Aside from this criticism, the game presents itself very well, with pick-ups being highlighted by a sort of Dead Space- style floating message. And at the risk of repeating myself, most the character models looked pretty snazzy.

Indeed, perhaps the best compliment I can pay Avatar so far is that the game made me feel pretty bad about all the creatures and plants I was destroying. Perhaps it's just the after-effects of a childhood spent watching Captain Planet (although I hated it at the time), but I really felt quite guilty as I used my flamethrower to torch a huge, colourful plant that was attempting bite my head off. Ubisoft says that there are no good guys and bad guys in this story, but my twitchy eco-sense tells me that this might not be quite the case. Either way, expect to fight some unusual beasties while playing as the marine. The main threat in the demo took the form of Viper Wolves - poisonous reptilian dog-type things, but the real highlight was the huge hammer-headed mammoth who showed up towards the end of the demo. Despite the clear danger he posed as he charged headlong into the hapless soldiers, his strange blue features made him slightly daft-looking - a quality that made me wince with regret as I fired a grenade into his face.

While the marine sections look to be very gun-heavy, Na'vi gameplay will apparently be much more focused around melee - with the bow and arrow being your only ranged attack. On a similar note, while the humans get to use flying machines and hefty mech suits with an infinite supply of bullets, the Na'vi will have several of Pandora's strange and wonderful creatures fighting on their side. Hopefully these distinctions should give the combat quite a bit of variety, because regardless of how well Avatar does in the cinemas, this game is going to be facing plenty of competition. Still, this is always the case for a new third-person shooter, and if even a little of the James Cameron magic has rubbed off onto this project, it should be well worth a punt for action fans.

James Cameron's Avatar: The Game will be released on all leading formats in December.