With production costs of an estimated US$100 million, Grand Theft Auto IV (GTA IV) is the most expensive video game production to date. So what does a hundred million dollars buy you? A stellar soundtrack, an impressive physics engine and much desired online play? One thing's for sure, you'd sure as hell hope it was worth it. At its core GTA IV is still very much the same game we know and love: gang banging, cop killing and jacking cars in a free-roaming world. Where the previous sequels took the GTA3 engine and built on top of it, GTA IV scraps everything that has come before, and rebuilds it from the ground up. Consider it almost a fresh start for the series - anything linking it to its predecessors, shy of a few references to the other cities, has been done away with.

Setting foot in the land of opportunity, Serbian immigrant Niko Bellic has arrived in Liberty City after reading his cousin Roman's constant tales of success and wealth in pursuit of the American Dream. Niko quickly discovers his cousin's tales were more than a little exaggerated; Roman works as a subservient cab driver, and lives in a roach-infested apartment. Niko is quick to reveal that his motives for arriving in Liberty City lie far beyond his cousin's obsession with titties and threesomes. A veteran of the Bosnian War, Niko is out to confront the demons of his past that have turned him into a shell of a man and will serve anyone so long as they can get him one step closer to his goal.

The early parts of Niko's journey attempt to ease you back into the swing of the GTA brand of gameplay through a series of short, sharp, tutorial-like missions that set up the basic plot. The difficulty is toned down to allow an easy introduction for new and old gamers alike. You won't feel the need to save your progress, although the game automatically does so after each mission or major story development, which is a welcome addition. The new mechanics are going to take some getting used to, with every element altered in one form or another.

GTA IV's wanted system is much more realistic than its predecessors. Commit a crime and a police search area will pop up on the mini-map. Rather than simply going to a pay & spray or collecting police bribes to lose the heat, players need to escape from the search radius and lay low until the wanted rating is cleared. The mini-map will display the location of the police in the area to give players a fair chance of escaping, though the search area will re-centre on your position if you cross the path of another cop. The size of the police search area will depend on the number of wanted stars - a one star rating is small and pretty easy to shake off, whereas a six star rating is difficult, but not impossible to escape from. The new system increases the intensity of police chases while maintaining gameplay balance, but it's not perfect. One notable problem is the fact that the police still tend to spawn out of thin air, which can be particularly annoying when you've just escaped a high wanted level.

Combat in GTA has always been a point of contention due largely to the use of an overbearing lock-on system. GTA IV rectifies the situation by adding a dynamic cover system, and two different aiming systems; a much cleverer lock-on system, and a free-aim mode. With a quick tap of the right bumper, you'll be able to hug walls, cars and pretty much anything solid. From there you can pop out to take shots at the right time, or blindfire if the action is too hot. Enemies have the same cover abilities, which can make them a little tougher to kill than before. It's rather annoying when an enemy won't pop out from behind cover until your back is turned, which can often result in a cheap death.

The new driving system is remarkably solid, and although generally more realistic, still has moments that defy conventional physics. Trying to fly around corners with handbrake turns isn't as reliable as in past games - it's more likely to send Niko through the windshield. Driving will feel different when you first play the game (a slight camera shift has the car sitting slightly to the right of screen as well as other changes), but veteran players will have no trouble adapting.

After the overwhelming state-sized setting of San Andreas, GTA IV brings the game back to its roots, limiting us to just a single city. Liberty City is nothing like the city featured in GTA3; instead it has been re-imagined to resemble the five boroughs of modern day New York City. The city is divided into five islands, linked by a series of bridges, tollways, underpasses and a rail network. The city mightn't be familiar, but Liberty City is still as simple as ever to navigate, thanks to the inclusion of a GPS system that will indicate the path to your destination right on the map. Fortunately, unlike the real world it's not just limited to the flashier cars on the streets, although they come with the added bonus of speech to guide you. Taxis are actually useful for once, as players can use them as a more legal means of getting to a destination with minimal fuss. You can sit in the back of the taxi and enjoy the ride, or pay a little extra to skip to the destination, saving time.

GTA hasn't been propelled into such acclaim based on its sandbox gameplay alone. It is the little intricacies that have made Rockstar succeed where impostors have failed and GTA IV is no exception. That trademark social commentary returns with a modern flair, tackling the paranoid shell of a city that is NYC today with hilarious results. Terrorist fears, dirty immigrants and troubled homophobes are the order of the day. Many of the existing companies have been retained and expanded like Cluckin' Bell and Little Lacy Surprise, even legendary radio host Lazlow makes a return. The level of depth creates a word full of personality and brimming with life that's easy to become lost in. Rockstar goes above and beyond what you'd expect. Rather than just letting you access a few webpages via ingame computers, you get the full experience of the internet, complete with spam emails and parodies of popular sites such as MySpace and Craigslist. Attempting to access certain sites, such as a 'child beauty pageant' site will result in an amusing response.

Entertainment in GTA has been greatly expanded, with a greater number of radio stations, as well television in your apartment and stand up comedy gigs in clubs around the city. The phone too has received an upgrade and plays an integral and fully functional role within the game and story. The phone actually has buttons, no longer just a source to relay incoming calls, allowing you to communicate with your buddies and get the latest goss. Upgrade to a fancier model and you'll not only get a camera in the package, but the ability to download blingin' ringtones and wallpapers. Not just a tool to be used for conversation, the phone has the added bonus of dialling 911 or roping in the special abilities of friends when the situation needs. Functional, integral, or just plain hilarious, the integration of modern technology adds an intriguing new level to the gameplay and delivers an absolute goldmine for that true Rockstar wit.

Players are eased back into Liberty City, and given a lot of time to adjust to the new features. The action doesn't begin to ramp up until the time the second safe house is unlocked, and even then, the difficulty doesn't approach that of previous instalments. Missions themselves are pretty common GTA fodder, with a lot of driving to 'insert location' to kill 'insert target' or collect 'insert item'. Where GTA IV succeeds above its predecessors is that the missions themselves are more engaging than ever before and in each and every mission, serve to shape the character of Niko. One of the key aspects of the series, and the sandbox genre as a whole, has been the freedom of choice. Typically, freedom in these games usually means being able to wander around aimlessly or choosing the order in which missions are done. GTA IV steps it up by giving the player the opportunity to make decisions that affect the way you progress through the game and alter the story. You get to decide the fate of a number of different characters, both minor and major. Minor characters allow you to decide whether you shape Niko to be a cold blooded killer, or simply a troubled man. Major decisions have significant consequences, and ultimately decide how the game will end. With major differences between each ending, it's certainly going to be interesting to see how they will continue the story through DLC or the inevitable next instalment. The new story branches are certainly enough to justify a replay through the game, but most importantly they allow you to bond with Niko and become engaged in his cause.

Chase sequences are a common occurrence throughout the game, but are more forgiving than before. Unless you're hopeless behind the wheel, it's unlikely the target will escape. Another factor to note is that the chase target is usually invincible until a pre-determined point in the chase, usually for story reasons. This had been done in previous games, but it just seems unrealistic and restrained, going against the freedom promoted by other aspects of the game. Perhaps it's the return to a single city environment, but by the end of the game, mission variety feels rather lacking, slipping into a mediocre familiarity.