Last week, at the Gamescom festival in Cologne, I got my first proper hands-on time with Battlefield 3. A five minute blast through the Operation Metro level during E3 provided a quick glimpse, but EA brought a 64-player PC level and a PS3 co-op stage to Germany; a great opportunity to assess the game's scope – especially after playing Modern Warfare 3's exciting Survival mode.

To show off the newly announced two-player co-op missions, EA Dice was running a level named Exfiltration. Set in a dilapidated corner of Tehran, the mission involves rescuing a PLR defector named El Zakir from a guarded apartment block. Our demo has one player taking on an Assault role, while the other goes Recon, with a silenced pistol and scoped rifle.

The action starts with the duo creeping through the lower floors of the block, simultaneously taking out small groups of guards, while also shooting down security cameras. If the alarm sounds, troops will swarm in making the rescue offensive much more difficult. Once we grab our man, it's back out into the streets to load him into a Humvee. Then we have to scout ahead, clearing the darkened street of enemy troops to provide a safe escape route.

It's an okay co-op experience. The different weapon and item sets tempt players to actually work together, rather than simply running and gunning side by side. In the final section, the Recon character is able to pick off the enemies on raised terraces and in upper windows while the Assault guy heads down the street clearing out the ground level. The earlier stealth sections are more disappointing, though, requiring little in the way of planning or tactical interplay. I wish we'd seen a more varied, more open co-operative mission, but as a taster, it was interesting.

Spawning into the 64-player Caspian Border map, the first things that hit you are sheer size and detail. Around our airfield there are acres of rolling grassland, sloping down toward a snaking river. On the other side, in the distance, there are threadbare woodlands and concrete buildings dotted about. A single track zigzags toward a bridge at the base of the valley. There is no sign of enemy activity, just an HUD showing the map's four conquest points. For a few second the eerie silence is broken as a helicopter zooms over, beneath it, the blackened vapour trails of speeding missiles.

A short tank ride later and we're in the midst of a skirmish around a wrecked military outpost. Heading up onto a rooftop, the crackle of gunfire surrounds me, above the trees I can see billows of smoke from another conquest point. Picking out enemy troops amid the shrubs and concrete blocks is tough; the Frost Bite 2 engine has been used to create an environment of lush, but naturalistic detail – lone soldiers blend easily into the flora. Meanwhile, the labelling of your own troops is subtle and easy to miss, so early on, every encounter involves a millisecond of confusion – usually, for me, it ends badly.

It is tense, exhilarating stuff, and it is no place for lone run-and-gun nut jobs. There are four classes to opt for – Assault, Engineer, Recon and Support – each with a huge range of weapons and items, easily selectable through a lovely smartphone-style user interface at the start of the session. They will all be vital components of a successful team. I can see Recon becoming key-team players, spotting and marking enemies so that they're clearer amid the foliage. The Support guys will also be valuable in larger battles, using light machine guns to lay down suppressing fire which causes the screens of nearby enemy players to go blurry. Tactical play is in the DNA of the Battlefield series, but it is absolutely paramount here.

There are stunning moments. Tank battles amid crumbling buildings, looking up while on a sniping mission to see dog-fighting jets zoom way over head. What Battlefield 3 does is emphasise the three dimensionality of the war zone; the soldiers, the snipers on rooftops, the choppers, the jets; a series of interacting vertical compartments. On a high-end PC, the detail and fluidity is breathtaking.

But yet, it is not over-powering. The sense of space means there are long periods between frantic face-offs. "We have the Swedish mentality of subtlety, of focusing on the right things – it's not a complete sensory overload," says producer Patrick Liu. "With Battlefield 3, we've been concentrating on creating the most authentic, the most physical, experience you've ever had in a first-person shooter. You are in the body of the soldier. But at the same time, it has to be playable – it's not realistic in some senses, not exactly…"

And this is an important point. It's weird writing about war games at the moment, knowing what's going on in the world, specifically right now, in Libya. It is troubling to use terms like 'authenticity' in relation to a game, where the parallels with brutal reality are confined to equipment, setting and noise. Yet it does feel much more as though the inspiration behind Battlefield has been documentary realism rather than Hollywood melodrama. In terms of tone and ambition, Battlefield 3 is the Generation Kill to Call of Duty's Inglourious Basterds.

The key is in the audio. Those echoes of distant gunfire, the metallic ringing din of your own assault rifle. Everything sounds as though it is being generated within a true 3D environment. The award-winning Dice sound team has been using a technique known as high dynamic range audio, which mixes sound effects in real-time for each player so that they hear the important stuff, rather than a barrage of noises all at the same amplitude. (There's a good slideshow of a GDC talk on the subject here.)

"In reality you don't hear all the sounds in your environment – you brain picks out a certain amount of sounds for you, which it thinks are important," says Liu. "That's what HDR audio does. There are footsteps, people talking, gunshots… but usually what really matters is the fact that you're being hit by bullets; when that happens it has a higher priority than all other sounds!"

The sound team has also structured the audio effects for different environments. Each weapon has a range of samples, depending on where it's being used, so that firing it in a forest will contrast heavily with firing it in a subway station, while a claymore will sound different on a dirt surface than on concrete. It's not a major gameplay feature, but it adds to the sense of detail and – that word again – authenticity.

EA Dice also called in a familiar figure to help with this aspect of the game. Andy McNabb, the ex-SAS author of Bravo Two Zero, has advised on both the campaign and multiplayer elements. "He brought a few things to the table," says Devin Bennett, of EA Games. "The way soldiers speak was one of them. They're always very positive 'we will do this', 'we will meet here' as opposed to 'we're going to try'… the banter at the start of the tank level we showed at E3 was all Andy. And there's the way they personalise their tanks – these things are their homes." McNabb also contributed heavily to the look of the Thunder Road tank level, providing EA Dice with photos of military outposts he'd spotted while on an MOD mission over the Iraq-Iranian border. Those buildings are now in the game.

"Oh and the other thing he told us is that guns are never clean," says Bennett. "You see all these military games with shiny guns… he said yours need to be dirty and beat up because they are in real-life. They've been through it."

On the last day on Gamescom, I managed to sneak into EA's community lounge with writers from FHM and the Sunday Mirror. Ill-advisedly, we gatecrashed a team deathmatch session being held for the winners of an ESL Battlefield tournament. This was a much more frantic experience, a taut urban face-off throughout the Operation Metro map. There are pitch battles across courtyard cafes, there are snipers in the windows of glorious Parisian terraces; great chunks of plaster are blown from historic buildings. Yet, it still feels more measured than Modern Warfare.

Here, I think it's down to the intricacies of the map design. In CoD, the arenas are designed for movement and insecurity – every cubbyhole has two entrances, every building is a route. From what I've seen, it's possible to bed down in Battlefield 3 – although campers are easily spotted, and the armoury range is there to flush them out. Yet still, it's the sense of time and space that is different.

So far, I've had just the slightest taste of these online experiences. I've yet to see how vehicle customisation works, or how the classes will be able to exploit the myriad equipment options. It will be fascinating to see how Battlelog functions to create a more social online gaming experience (and how it will compare with CoD: Elite). Also, I haven't flown a jet. But what I have found is a cutting edge re-interpretation of what made Battlefield 1942 so enormously enjoyable and compulsive all those years ago; vast, detailed maps, tactical depth and the ability to play as you want, within an environment that offers many possibilities. That is Battlefield.



Battlefield 3 is released on 28 October for PC, PS3 and Xbox 360.