The following review is spoiler-free.

It always starts like this: a wooden yellow barrier, men in uniform, and a crowd of curious civilians at the circumference of a tragedy. Come rain or shine, domestic spat, serial killing or accidental overdose, the rubberneckers are a constant presence throughout your time in LA Noire. They stand at the boundaries, gossiping and craning to catch a glimpse of the corpse. They don't really care about the victim - who they were or how they died. They just want to take a good look.

And yet as much as we may look down on these gawkers, their morbid nosiness is ultimately equal to our own. Team Bondi and Rockstar understand this all too well, and LA Noire is an unrelenting exercise in feeding that appetite for death. At the same time, it is also a game that delves deep into our love of detective movies - just as Red Dead Redemption did for the Western this time last year.

But despite what some people may be expecting, this isn't another open-world action game in the vein of Rockstar's previous heavy-hitters. There are similarities, certainly, but the core gameplay is generally closer to the likes of Heavy Rain or the Phoenix Wright series than to the gunfights and vehicle chases of Bellic and Marston. Prior to playing the final code, one of my biggest concerns with LA Noire lay with how the action would be handled; it was clear from early on that Team Bondi was going for a measured, thoughtful approach to the investigative scenes, but how was that going to mesh with the moments where the bullets started flying? It seemed inevitable that the game would have them, but how many baddie-packed scenes could the story sustain before the illusion of reality came crashing down like a house of cards?

As it turns out, Team Bondi's solution has been to make combat an entirely optional affair for the majority of the game. As you drive about the city, soaking up the meticulous splendour of 1947 LA, your colleagues at Dispatch will alert you to crimes taking place in the nearby area. Accept, and you'll race across town to engage in a quick bout of terse violence - a botched robbery, perhaps, or a personal disagreement that's led to someone sprouting a triplet of leaky holes in their chest. As soon as you've completed the self-contained episode, it's back to the heart of the game, to the thoughtful world of procedure and inspection. And, if you never took the call, it's a world you never left in the first place.

The point I'm trying to make, in long-winded fashion, is that plot and character are the bricks and mortar of LA Noire. The story begins in strangely staccato fashion, introducing protagonist Cole Phelps and ushering you through a smattering of brief assignments as a patrolman. Eventually you'll pass through four major crime desks - Traffic, Homicide, Vice and Arson - but before then it's time to learn the basics. Here, at the bottom of the food chain, you'll be trained to dissect a crime scene, which in turns means learning to listen for the subtle cues that guide your efforts: sleuth-y music to indicate the presence of clues, and soft piano stings to denote the presence of an item that can be inspected.

At the touch of the button you'll closer inspect the object in question, turning it over in your hand with gentle manipulation of the left analogue stick. If there's more to it than what initially meets the eye, vibrations will guide you to a sweet spot that will then reveal further information. Useful observations are jotted in Phelps' notebook, and in the early days useless objects will be greeted with some form of dismissive comment from the man himself. Later in the game these aids will disappear, but by this point you'll have a natural instinct with regards to the items that litter each crime scene. You'll walk in, survey the surroundings, and make a bee-line for the trinket that stands out like a sore thumb.

Physical clues aside, the bulk of your discoveries will crop up during face-to-face interviews with suspects and witnesses. You'll choose a topic for discussion from your pad, press the interviewee, and then watch their face for a response. Depending on how the subject acts, you choose to react with one of three responses: truth, doubt or lie - the latter requiring you to produce an item of evidence to back up your claim. There's a bit of a learning curve here; it's usually fairly obvious when someone is telling the truth, but it's often harder to tell whether someone is merely being evasive (requiring doubt) or actually telling you an outright porkie pie.

The suspects in early cases give the game away quite easily, for obvious reasons, but before long you'll find yourself profiling suspects on an individual basis, contrasting their current reaction with those you've already seen. It's in this manner that you'll decide whether that young Communist agitator is glaring at you because he's telling the truth, or because he hates your guts and wants to stay clammed up.

Naturally, this kind of gameplay is only made possible by Rockstar's much discussed MotionScan technology. I'm not usually the kind of gamer who dribbles all over this kind of thing, but the fact remains that the end result here is little short of groundbreaking. Games like Uncharted 2 and Heavy Rain have already made massive leaps in this area, but after LA Noire it seems unfathomable that we'll ever be able to sit through cutscenes packed with jerky mannequins and wooden dialogue. The quality of acting on display in a single case is enough to trump the vast majority of top-tier games; when you consider the complete selections of believably flawed miscreants - the mobsters, perverts, and barflies - there's a strong case for this being one the strongest NPC casts we've ever seen.

And yet as impressive as MotionScan is, it's arguably the underlying infrastructure that makes the game work as well as it does. I've already covered the neat design of the investigation mechanics, but there's actually a similar degree of thought behind every aspect of play. There's an in-built hint system in place, masked as "Intuition", which acts like a Raymond Chandler version of the simplifiers in Who Wants to Be a Millionaire? These powers only ever make your life easier, rather than giving you the answer outright, and their use is inherently limited. As you successfully interview suspects, complete Dispatch quests and visit landmarks dotted around the map, you'll earn XP which slowly fills a Rank meter. Level up, and you'll either earn an intuition point, or unlock some other form of reward - a new suit for Phelps, or hidden cars to find scattered about the map.

If there's one aspect of LA Noire that the hardcore will struggle with, it's this inherent accessibility. Even if you ignore the option of Intuition, this isn't a hard game. Screwing up at a crime scene or interview won't end your game, but instead force your investigation onto a different path, demanding that you find the answer elsewhere. As the case was with Heavy Rain last year, it's important to resist the gamer's instinct to reload when things do go wrong, because the ongoing struggle for the truth is what drives the game onward. Frankly, it's quite remarkable how adept the game is at cleverly shuffling its narrative threads. The very first interrogation you conduct resorts to a spot of suspect amnesia if you foul up, but from that point on it your efforts invariably feel like genuine organic detective work.

One of the very real pleasures of LA Noire is the manner in which it subconsciously teaches you to follow a set procedure. By the time you reach Homicide you'll know the drill: show up at the scene, speak to the coroner and attending officer, then take a look at the evidence before you chat to the witnesses. As subsequent clues reveal themselves, you'll make a habit of using Gamewells - roadside telephones - to call on supporting services back at HQ. You'll know that when you show up at an apartment, the mailboxes will show you whose door to kick down.

We've had games that let us play cop before, of course, but it's hard to remember anything that's ever come this close to making us feel like we're actually doing the job. I could have spent half of this review going on about the banter Phelps shares with his four partners - you get one on each desk, and they damn near steal the show - but as much as I love these cynical, hard-drinking antiheroes, they're only part of the big picture. In the end, LA Noire is much more than the sum of its parts.

With a project this ambitious, it's only natural that some of these parts fare better than others. Given how incredible the game looks, it's easy to forgive the rare occasions (on Xbox 360) when the frame rate dips a little, or when a texture pops in a little later than expected. The investigation mechanics shine, but the handling in higher-tempo sequences may not be to everyone's taste. While the controls for on-foot pursuit are excellent, utilising a system that's not too dissimilar to Assassin's Creed's Free Run trigger, melee combat has been boiled down an overly simple timing exercise.

Gunplay is handled more competently, with a simple-but-solid take on established cover systems, but it's still a good thing that it doesn't crop up too often. Prolonged shoot-outs are usually reserved for the most significant beats in the sprawling plot, ensuring that they still feel like a big occasion when they do crop up. There are some pleasingly creative settings for several of these battles, too - don't worry, I won't spoil anything. It's a shame that explosive barrels make an unwarranted cameo, but thankfully you'll soon forget all about them.

There are other quirks and gameplay one-offs that pop up across the 24-odd hour duration of the story, but really these little diversions are just icing on the cake. On a similar note, the collectible cars feel like superfluous bonuses given how consistently excellent the main story is - and thanks to the malleable nature of case progression, there's more than enough content to warrant a second trip-through.

Even without the prospect of alternative leads, missed conversations and the like, you'd probably still want to see it all again. There's something entrancing about the way this game plunges you into the violence, the corruption, and the sadness of post-war Los Angeles. Each of the four major desks has a remarkably different tone, and while the slow reveal of Phelps himself is the major narrative thread, it's equally true to say the dark heart of the city itself is an equally important protagonist. As you stoop to inspect the naked body of a mutilated young woman, as you shakedown a gambling racket in a dusky backroom, as you pick through the skeletal cinders of a burnt-out building... as you do these things, you'll silently admit the truth: you don't want to stop the bleakness, you want to revel in it.