One of the many things that set GTAIV apart from its predecessors is Liberty City, which is more convincing as a living, breathing urban environment than anything that you've seen in a game before, and bears little resemblance to its namesake in 2001's GTAIII. Liberty's diverse population believably attempts to go about its daily business, seemingly unaware that several criminal factions are at war in the city. Niko has no such luck. He's compelled to start working for one of the factions shortly after arriving, when he learns that his cousin Roman has some potentially fatal gambling debts. Niko's military experience makes him a useful freelancer for employers in the business of killing each other, and though his reluctance to carry out their orders is often apparent, he does whatever is asked of him in the hope that completing missions for other people will ultimately give him the means to complete his own.
Actually, Niko doesn't have to do everything that is asked of him. On several occasions as you play through his story, you'll be presented with decisions that afford you the option of doing what you think is right rather than blindly following instructions. You don't necessarily have to kill a target if he or she promises to disappear, but you have to weigh the risk of your employer finding out against the possibility that the person whose life you spare might prove useful later in the game, or even have work for you in the form of bonus missions. To say anything more specific on this subject would be to risk spoiling one of GTAIV's most interesting new features, but suffice it to say that every decision you make has consequences, and you'll likely want to play through the game at least twice to see how the alternatives unfold.
Grand Theft Auto IV's story mode can be beaten in less than 30 hours, and there are so many optional activities and side missions to take part in along the way that you can comfortably double that number if you're in no hurry. The majority of the story missions task you with making deliveries and/or killing people, and play out in much the same way as those in previous games. With that said, most of the missions are a lot easier this time around, partly because Niko is a more agile and efficient killer than any of his predecessors, and partly because the LCPD seemingly has better things to do than hunt down an illegal immigrant who's gunning down undesirables all over the city. Some of the more imaginative missions sprinkled throughout the story include a kidnapping, a bank heist, and a job interview. The cinematic cutscenes associated with story missions are superbly presented and are the sequences in which the game's characters really shine. Without exception, the characters you encounter benefit from great animation, great voice work, and superbly expressive faces. They're not always so impressive when they join you on a mission and refuse to do what they're supposed to (for example, not following you on an escort mission, or failing to negotiate a doorway). Nevertheless, these problems are few and far between, and they're made less painful by the new "replay mission" option that you're presented with whenever you fail.
When you're not running missions for criminals, taking part in street races, stealing cars to order, or randomly causing trouble, you'll find that there are plenty of opportunities to unwind in Liberty City. Some of these optional activities offer tangible rewards that can prove useful in missions later on, whereas others are just a fun way to kill time and take in more of GTAIV's superb humor. For example, you can watch television, listen to numerous different radio stations, check out some genuinely funny shows (including some big-name acts) at cabaret and comedy clubs, and use a computer to surf the in-game Internet.
GTAIV's Internet is filled with spoofs of all the kinds of Web sites that you'd only ever look at accidentally or when you know there's no danger of getting caught. Some of them can be found only by clicking on links in spam e-mails, whereas others are advertised prominently on the search page. There's plenty of amusing stuff to find if you spend some time in one of the "TW@" Internet cafes, but the most interesting site by far is an online dating agency through which you can meet women who, if they like your profile, will agree to go on dates with you. Dating and socializing with friends is something you can spend as much or as little of your time doing as you like, and though the people you meet can occasionally be demanding to the point that they become irritating, keeping them happy invariably benefits you in some way.