James Cameron's Avatar project has long been shrouded in mystery, but now as both the film and its video game counterpart approach their December release dates, things are becoming a little clearer. We're getting a feel for the Na'vi, the 12ft tall blue aliens who dominate the film's advertising, and for Pandora, the lush jungle planet they call home. We're also getting a sense of Cameron's key theme, the conflict between nature and technology. Finally, we're also finding out exactly what Ubisoft has been doing with all this source material over the past four years.

As covered in the last preview I wrote, Avatar the Game is a third-person action adventure that casts you as a member of the RDA - the human military force that's attempting to gather important natural resources from Pandora. Thanks to a lengthy session I spent with the game last month, I can now reveal a few more details about this setup. The player takes control of a chap named Abel Rider - a communications specialist who's been brought in to help find a particular sacred spot on Pandora. It's not yet clear what this place is or why the RDA wants to get there, but right from the start it's clear that Rider will have other problems to handle - particularly the fact that someone within the RDA camp is feeding information to the Na'vi, who are getting increasingly upset with the human presence in their back yard.

The game kicks off at a military base with a short introductory section that serves to introduce both the controls and some of the back story, particularly the whole concept of Avatars themselves. In short, the RDA has been creating genetically engineered human-Na'vi hybrids that can be controlled remotely from machines known as link beds. These Avatars are extremely useful, as humans are unable to breathe the air on Pandora, but only one in a million people have the right DNA to be able to sync with one. And as luck would have it, Abel Rider is one of these lucky few.

As a tutorial this short interlude works well enough, but the dull corridors and electronic doors instantly fade from memory once you arrive in Pandora's wild jungles. It's clear that a lot of effort has been spent on the game's look, and you'll immediately appreciate the level of detail on both Rider and his surroundings. Last time around I was playing on a 3D-enabled TV, and under those circumstances the lush environments really felt like they had a lot of depth; you don't quite get the same immediate level of immersion on a standard set, but you do certainly get drawn in by the sheer mass of flora and fauna that surrounds you. If you're curious about something, Rider has the ability to scan nearby objects and creatures by holding down the right bumper (I was testing a 360 build), and once you've done this to a new discovery a fresh entry will be added to the PandoraPedia - an in-game database that provides further details on content and concepts.

If on the other hand you're feeling a tad destructive, you'll soon realise that opening fire on the environment will net you a small reward. Every time you destroy something, whether it's a hostile threat or just part of the jungle, you'll earn an XP bonus that will eventually help you to upgrade your equipment. If you run around blowing up everything you see, you'll rack up points quickly- but it may turn out that this isn't such an appealing approach; while the RDA see the jungle and its contents as an active threat, something to be neutralised and cut back, the Na'vi know it as their home. The RDA's quest for resources has set them on a head-on course with the alien locals, and sooner or later you're going to have to make a choice about whose side you're on.

Na'vi gameplay feels odd compared to the RDA side of things

I've yet to really go hands-on with the Na'vi-based gameplay, but I'm now beginning to get a good feel for the RDA's side of the picture. The human forces in Avatar take a technology-focused approach to combat, and at any given time Rider can have four weapons mapped to the points of the D-pad. At the start you're limited to comparatively straightforward firearms like pistols and assault rifles, but as you earn XP you'll unlock bigger and stronger guns, as well as toys like flamethrowers and grenade launchers. Combat itself has a swift, arcade-like pace. Rather than being a Gears-like cover fest, Avatar encourages you to dash about, making full use of a pouncing dodge move and a screen-blurring 180 degree turn. Surprisingly there's no lock-on system, so it's up to you to handle the targeting, manually - and some of your foes, like the canine ViperWolves, are pretty good at giving you the run-around.

It's clear that Ubisoft has deliberately moved away from the prevailing trends with this combat model, but it still feels quite strange to have such an old-school system. On the plus side, this swift pace is seemingly echoed by the game's approach to objectives and questing. From what's been shown so far, it seems that Avatar's world is built out of large and relatively open play areas; the first "proper" level is made up of several interconnected hubs and clearings, separated by branching valleys and pathways. In other words, it's not a massive flat open plain, but there are plenty of places to go. More importantly, there are plenty of things to do. My main story objectives took the form of simple assignments like searching for a missing trooper, deploying equipment at certain locations, but between these jobs there were lots of optional tasks - from killing a certain number of specific enemies, to activating markers that can be used to warp about the map. The latter proved surprisingly useful, as there can be quite a bit of ground to cover between waypoints at times.

Rather than having long, drawn-out quests, Avatar seems to favour punchier goals that logically connect. You go to search for a colleague, then you find him and he asks you to deploy a pair of transmitters for him. As you do this you hear that your camp is under attack, so dash back to take command of a massive turret at the main gates. In this opening section at least, the game seems pretty good at changing things on a regular basis, throwing in new vehicles and toys; as you'd expect from the man who brought us Aliens and Terminator, a lot of these machines look very cool - particularly the stomping mech suits with machine guns on their arms. Controlling an Avatar, on the other hand, is a very strange experience: after getting Rider to climb into a link bed, you'll suddenly find yourself in control of a lanky blue hybrid in an odd-looking brown uniform. You run and jump like the wind in this role, but your primary weapon is still a machine gun. Perhaps it's just the way that you tower over your human buddies, but there's something quite jarring about this sudden shift of character. Then again, maybe it's supposed to feel that way.

Aside from this oddness, my only real concern with Avatar is that it feels a bit lightweight. The detail is certainly there, and the plot certainly has traces of that Cameron sci-fi magic, but I'm not yet convinced about the gunplay. Perhaps I'm just too used to the current cover-and-blind-fire trend, but without a lock-on or zoom aim the shooting felt a bit lacking in precision. Still, the visuals are certainly looking great, and there's still plenty we've yet to see - particularly the Na'vi gameplay, with its emphasis on close quarters combat. The finished game is due for release on December 4, so check back here soon for our final verdict.

James Cameron's Avatar: The Game will be released on all leading formats on December 4.