Is GTA: Chinatown Wars my favourite handheld game of all time? It's a question that I asked myself many times while playing through Rockstar Leeds' gangster epic for the second time this year. I loved every second of the original DS release, and I ranted and raved about it to anyone who would listen, so I jumped at the chance to return to an improved version of the game for PSP. And guess what: it's every bit as good as it was last time around, if not better.

Chinatown Wars is a bit like a crossbreed of GTA IV and the very first Grand Theft Auto game - the rock-hard, top-down 2D title that kicked things off back in 1997. The game itself is entirely 3D, but the action is viewed from an elevated, near-overhead perspective. The series' trademark humour is here in abundance, as are several other familiar features that have come to define the franchise over the years - the perpetual car-jacking, the sideshow mini-games, and the hidden collectibles stashed all over the city. But there are also new elements here too - notably a tendency towards shorter, bitesize missions, and a hugely endearing sense of playfulness.

Naturally the whole package is wrapped up with a twisting, thriller-style plot. Chinatown Wars is the story of Huang Lee - a spoiled brat who arrives in Liberty City shortly after the murder of his father. Lee is supposed to deliver a ceremonial sword, Yu Jian, to his eccentric Uncle Kenny; by giving the weapon to the ageing leader of the Triads, Kenny hopes to guarantee his position as heir to the throne. Unfortunately things go tits up as soon as Huang arrives: he's ambushed by thugs who promptly shoot him in the head, nab the sword and leave him for dead.

This ill-timed theft creates a serious problem, as Kenny is left looking like a complete idiot. His rivals in the Triad leadership immediately overtake him in the race to be the next leader, and to make matters worse it seems that there's a rat in the organisation. Things get messy very quickly, and as the bodies pile up Huang finds himself desperately searching for the traitor - who may or may not be the same person who killed his pops.

In structural terms, Chinatown Wars is very similar to previous GTA titles, with Huang being passed from boss to boss as everyone tries to wash their dirty (Chinese) laundry. Huang himself is a very likeable anti-hero - a sarcastic smart-ass who's clever enough to know he's in serious trouble, but not powerful enough to do anything about it. He's surrounded by a cast of great characters, from arrogant psychos to junkie undercover cops, and while the plot unfolds through static but pretty-looking cutscenes, the written dialogue is sharp enough to make this the funniest GTA in quite some time. You'll frequently laugh out loud while playing this game, but the darker elements of the plot work equally well - particularly in the story's latter half.

In gameplay terms, it's back to the old template of driving around town and picking up missions from hotspots on the map. The city layout here is identical to GTA IV (minus the Western-most island), and despite the change of viewpoint you'll easily be able to recognise the different areas - particularly due to the fact that the excellent graphics are sharper and more detailed on the PSP than they were on the DS. All of the game's menus and settings are accessed via a simulated PDA-style interface, and among the many features is a handy GPS system that helps you find your way to important locations and people. Huang's PDA also allows him to receive emails from his bosses and from his drug-dealing contacts (more on these later), and there's a handy little menu that lets you order weapons over the internet: two minutes after placing your order, you'll get an email saying that your package has been despatched. Head to your nearest safehouse, and your guns will be waiting for you in a box. If only Amazon worked so well.

As many of you will be glad to hear, the driving controls are considerably easier to pick-up here than on the home console GTAs. There's an automatic steering system that helps to keep your vehicle parallel with the road, but this actually proves to be very handy (and you can turn it off if you really hate it). On foot things take a bit more getting used to due to the rather odd camera movement and slightly fiddly lock-on combat system, but once you've adjusted you'll forget all about these things. By default Chinatown Wars uses the analogue nub to govern your movement; personally I found this very uncomfortable, but thankfully there's an alternative setup that lets you use the d-pad instead.

Outside of the standard actions, you'll also find yourself doing a whole lot of unusual things - from hotwiring cars to rummaging through bins to assembling sniper rifles. On the DS, all of these activities were conducted via the touch screen - a design quirk that I absolutely loved the first time around: one minute you'd be swiping the stylus to smash the lock off a security gate; the next you'd be rubbing the screen in a bid to perform heart massage to a dying man in the back of a stolen ambulance. This PSP version uses a combination of the shoulder buttons and the nub to replicate these actions, and I'm happy to report that they work almost as well. You don't get quite the same feeling of interaction, but you do get the same sense of glee when you make your first Molotov - and that's what counts.

It would spoil the fun to reveal all the things you'll do in Chinatown Wars - and in any case, it would take me ages - but let's just say that the game boasts some of the most inventive missions in GTA's history. Niko Bellic's adventures occasionally leant too heavily on the "go to place A, kill person B" mission template, but here you'll rarely be bored. It's quite a tricky game, however, and you may hit the odd difficulty spike, but there's nothing here that'll keep you stuck for long. When you do fail a mission you're immediately given the option to restart, and there's usually a "skip trip" option to save you traipsing across town. If you particularly like a mission you come across, you can also replay old assignments via a noticeboard in Huang's apartment. This is a long overdue feature for GTA games, so let's hope it becomes a standard issue for future titles.

While we're on the subject, Rocktar, I'd like every new GTA to include Chinatown Wars' drug-dealing mini-game. It's fun, it's satisfying, and it's almost my favourite thing about the whole package. In essence, dealing in this game works a bit like stocks and shares - only you carry the goods yourselves, and the cops will kill you for doing it. Huang is forced to start selling drugs early on in the game's plot, and from that point on it becomes your main source of cash flow. As you explore the city, you'll spot little blue dots on your radar; go and visit them and you'll find a dirty new friend who's eagerly waiting to sell you something. A handy little buyer's guide will tell you whether what you're getting is a good deal, and how much profit you stand to make. Buy low, sell high and you'll make a fat little profit.

As Wez said in his review of the DS game earlier this year, the whole drug-dealing element of Chinatown Wars is surprisingly full-on. You might expect a handheld GTA to be less "colourful" than its home console counterparts, but if anything it's actually more twisted than what we've come to expect. You'll get an email from a friend saying that he and his friends need some coke, so you drive around town collecting as much of the white stuff as you can. Then you head over to your contact, offload the stuff for a massive profit, and use some of the cash to load up on skag. It's immensely satisfying when you pull off a massive deal, and since there's always a risk that the deal will be crashed by the police, you're never 100 per cent relaxed. With past GTAs, being arrested was little more than a nuisance; here it's a threat to your livelihood. Oh, and the banter with your fellow dealers also contains some of the nastiest, most bleakly funny dialogue to ever grace a video game. "I was gonna use the ecstasy for personal entertainment," says one, "but if you want it, I'll just jerk off later instead."

I'm running out of time, and yet there's still a lot of stuff that I've not covered. There's the new wanted system, evolved from GTA IV, which lets you lower your wanted level by trashing the cop cars that pursue you. There's the fantastic soundtrack, now boasting an extra six radio stations exclusive to the PSP, giving us a total of 11 options; each is mixed by a guest artist, and the contributors include Deadmau5, Tortoise and DFA Records. There's the never-ending hunt for CCTV cameras to destroy - Chinatown Wars' equivalent to the obligatory collectibles. There's the new PSP-only character - a deluded reporter with a death wish.

But you know what? I'm not going to say any more. I'm just going to say this: after thinking about it for a bit more, there's no doubt in my mind. GTA: Chinatown Wars is my favourite handheld game of all time. It's funny, it's full of great ideas, and above all else it's wickedly fun. Whether you're a GTA veteran or someone who's never played one of these games before, you should know that this is one of the best titles available for your PSP - or, indeed, for your DS. To miss it would be criminal.