Konami; PS3, PS4 (version tested), Xbox 360, Xbox One; 18+; £24

The most impressive thing about Metal Gear Solid V: Ground Zeroes' opening cutscene is its brevity. This is a series that, for all its brilliance, is equally known for over-indulging creator and director Hideo Kojima's cinematic leanings; a weakness that reached a nadir with 2008's Metal Gear Solid 4, a nearly-amazing game smothered by exhaustingly long interstitials.

Ground Zeroes opens with a long tracking shot of the main antagonist in a prison camp. The next few minutes showcase the new standard of animation tech from the top-tier Kojima Productions – individual fingers waggle, eyes track with subtlety rather than staccato movements, and facial movements add a convincing emotional resonance to every line. The whole thing is over in a few minutes, and all the more powerful for it. Finally, it seems, Kojima has learned that less is more.

And how true that turns out to be. The most divisive aspect of Ground Zeroes is undoubtedly its alleged length, which depending on your source is anything from ten minutes to two hours, and its strange status as a Metal Gear Solid and the prequel to a real Metal Gear Solid. What all this means is that Ground Zeroes is the opening act for a game, The Phantom Pain, that will be released at some yet-unknown point in the future, and as such consists of only one (sizeable) location and a series of missions and challenges to be carried out within it.

Put so baldly, this can sound like a raw deal and, when the credits roll after a few hours on the main mission, feels like it too. Then you return to the main menu and at the bottom see Completion ranked at nine percent. Which doesn't seem to add up. Kojima Productions' greatest mistake with Ground Zeroes is rolling the credits so early, because it makes the opening of the game seem like the entirety – your instinctual thought is "that's it?"

Of course it isn't. Ground Zeroes has six missions in total that unlock as you play, which in turn are unlocking more gear and extras and challenges as you go through them.

The big problem is the single environment, because though this is quality over quantity it's also pushing that concept to the limit. Nevertheless this 'military prison' is a fantastic space, stretching across a long and curving rocky coastline, incorporating various makeshift camps, holding cages, countless minor buildings, and a fortified complex. There are great dips in the landscape to crawl through, craggy outcrops to clamber, and smooth open spaces where enemy sightlines are long and unfettered. I've spent days creeping around it and am still finding new things, not to mention that the layout is remixed for each mission.

This focus on mastering a setting plays into one of Ground Zeroes' biggest changes to the MGS formula - a pair of "binoculars" that can be brought up instantly at any point, and used to listen into chats and "mark" foes who stay that way permanently. Such visual aids may be anathema to the hardcore crowd, but it's a mechanic that plays right into Metal Gear's strengths and doesn't cheapen the enemy threat one iota. Sneaking around in soldiers' proximity is incredibly tense, and the surround sound is superb at letting you pick out not just direction and distance but even the surface an enemy's walking on.

In a sense everything is staked on the AI, because Ground Zeroes has to be surprising in countless different configurations. These soldiers are a great mix of rote behaviour and kinks, with the traditional set patrol routes mixing into oddities like sniffles and what can be an incredibly distressing habit of checking over their shoulders. They also, if checking out something suspicious, radio command to say what they're doing – and if they suddenly go quiet, others will be coming to check out why. This 'connected' quality extends across the opposition – at one point I shot down a surveillance camera with a silenced pistol and, as I was congratulating myself, enemy command instructed the nearest troops to go and find out why it had stopped transmitting.

Other innovations include 'reflex' moments; when spotted, the game moves into slow-motion for a few seconds during which you can headshot that enemy to avoid them alerting command. The idea is great but it's the implementation that takes it home, with rounds moving slowly through the air as bullet casings cartwheel out, and a squelchy sound effect for "successful" shots that's equal parts disturbing and a relief.Ground Zeroes is more than anything a showcase for imagination, experimentation, and play for play's sake, because there is simply so much to do in and around this environment.

It's not a game where following the objective markers gets the best results. No mission actually forces you to silently steal a truck and drive around the base under the speed limit – though if you do, the enemy soldiers won't take a second look. Or perhaps you'd prefer to nick a tank and just blow everyone away. Personally, I enjoy setting multiple C4 charges around the main helipad, walking out and, as the enemies congregate, pushing that button and calling in my chopper – which descends to Wagner's Ride of the Valkyries.

I don't usually share progress stats in reviews, because it's a slippery slope and mostly irrelevant, but in the case of Ground Zeroes I've been playing fairly solidly over three days and sit at just over 40% completion. There are concerns about only one map, which by some lights are justified, but the idea that this delivers only a few hours of entertainment is grossly unfair – not least because Ground Zeroes marks a new kind of real-world engagement in the work of Hideo Kojima and Kojima Productions.

One of the contradictions that makes Metal Gear such an interesting series is the central theme of war being a great evil, one that creates more monsters than it ever destroys, rubbing up against what can only be called a fetish for military gadgets and hardware.

The Metal Gear games are set in a version of the real world's history, where dates and facts are closely observed, which leads to Ground Zeroes' missions beginning with the designation of 'pseudo-historical accounts. But this is clear: 'Ground Zeroes is explicitly 'about' and based in Guantanamo Bay. And as the repeating structure and evolving narrative are at pains to point out, black sites like this and their grey legal status are a tribute to bureaucracy's unerring ability to triumph over ethics and what is "right" - just ask President Obama. If Kafka was alive today he'd be writing about Guantanamo, but instead we have Hideo Kojima and an irony; a medium predicated on interaction, a game about tactical espionage action, with an overarching theme of political inaction.

Some of what we witness in this camp really tears the mask off the follies our governments commit in the name of war, and the injustice (or extrajudical-ness) of Guantanamo Bay's continuing existence. The name 'Ground Zeroes' is in part a reference to a Metal Gear character, Zero, which in turn is a British military callsign meaning HQ. Hideo Kojima loves multi-layered titles, so here we have not just the traditional meaning of "ground zero" – a starting point for MGSV: The Phantom Pain – but an indication of Zero's connection. Ground Zero is also notable as contemporary shorthand for the ruins of the twin towers, so drawing a line and equivalence between 9/11 and the existence of Guantanamo.

Beyond even that, Ground Zeroes holds what little moral this collection of stories has. The prisoners you find in one part of this game's map are locked in cages, manacled, with bags over their heads and identical yellow jumpsuits. Stick around and you'll hear the guards, when patrolling these areas, refer to them as animals – "mutts". From interrogation tapes you acquire, and their delirious mumblings as you carry them out, it is clear not one has survived the experience without being somewhat mentally broken by it.

As the game makes clear over and over, these are legally non-people, stateless individuals that nobody wants and nobody is coming to save – except in a video game. They are non-people being gradually broken-down because that's what this place exists for; the ground-down zeroes of Ground Zeroes. It is surprising, and not a little depressing, that all people want to talk about with this game is the running time.