"I have a deep sadness in me, Luis. Will you join me, please, for an orgy of champagne, cocaine, women, watermelons and whatever else this city may have to offer?"

These are the words of Yusuf Amir - spoiled rich kid, property magnate and part-time arms dealer. Yusuf likes many things - prostitutes, class A drugs and stolen military hardware - but most of all he likes to have fun. The invitation I just quoted is taken from one of the early missions in The Ballad of Gay Tony, and in many ways it sums up what this episode is all about. Like The Lost and Damned, and GTA IV before it, TBoGT is ultimately a story about flawed, messed-up people - but this time the melancholy is all but overwhelmed by a massive streak of hedonism.

Yusuf himself is one of many elements that make this an extremely successful add-on. Thanks to the vocal talents of comedian Omid Djalili, Yusuf is a colourful and hugely endearing character - a maniac playboy who'll equip you with ludicrously powerful weapons before sending you off to steal police tanks and rocket-spewing helicopters. In short, he's a party animal - and his infectious enthusiasm underpins the spirit of Rockstar's final GTA IV episode. The player takes on the role of Luis Lopez, the Dominican-American bodyguard and business partner of Gay Tony, Liberty City's number one nightclub owner. Tony owns both Hercules and Maisonette 9 - respectively the hottest gay and straight clubs in town - but his personal life is in tatters. He's a hopeless, drug-addled mess, surrounded by leeches and hanger-ons, and he owes vast sums of money to two separate sets of gangsters.

It's a typical GTA setup, with a violent but otherwise intelligent antihero surrounded by a cast of incompetent lunatics. However, in a serious departure from the adventures of Niko Bellic and Johnny Klebitz, TBoGT seems hell-bent on serving up ludicrously over-the-top scenarios with every mission. Some 10 minutes into the game you'll be racing across town in a golf cart as angry mobsters give hot pursuit; later on you'll find yourself climbing to the top of a Space Needle-like tower, gunning down police choppers with a shotgun that fires exploding shells. Later still you'll enter a race that starts with the participants jumping out of a helicopter; you'll parachute right into the cockpit of an awaiting speedboat, tear across the waves, and eventually transfer to a juiced-up race car that features a screen-blurring turbo boost.

Most of the missions are crazy

For the most part there is very little filler in terms of mission design, and the campaign is jam-packed with wild set pieces. On occasion the chaos seems to be almost too much for the game's ageing engine, resulting in a noticeable drop in frame-rate, but thankfully this never becomes a serious problem. The action here is also notably harder than GTA IV, to an even greater extent than was the case with The Lost and Damned, but it's all so much fun that you're unlikely to be too bothered about the odd restart. As with TLaD, there's a smart checkpoint system to skip you past the bits you've already done; there's still the minor hassle of having to re-arm before returning to the fray, but thankfully you can call one of Luis' buddies to get weapons and armour delivered on demand.

Outside of the main plot there's also a generous selection of side attractions. There's a golfing mini-game, an underground fight club to bet on or take part in, and the aforementioned multi-vehicle racing. There's also a base-jumping mini-game built around the new parachute mechanics, allowing you to take part in 20 jumps at locations dotted around the city. The controls here feel like an update on Nintendo's classic Pilot Wings series, allowing you to steer your descent by shifting your weight and using air-brakes. The mechanics are easy to pick up but hard to master, so it's supremely satisfying when you manage to pull off something flashy - like landing on the back of a moving truck, for example.

There are some neat new multiplayer modes too

In a further bid to make TBoGT feel a bit different to previous GTA offerings, Rockstar has thrown in a set of simple diversions at Tony's clubs. You can shake your tail feather on the dancefloor (a simple rhythm game), join a champagne drinking competition (which involves rapidly rotating the right thumbstick), or go on management duty - a job that requires little more than walking around the club to keep an eye out for trouble. Every so often you'll be sent out on a mini-mission to help one of Tony's clients, but aside from these moments the club games are slight. Still, that's the point - they're just another little way in which Rockstar has tried to give a TBoGT a fun vibe.

It's also worth pointing out that there's a lot of sex in these club-based activities, and indeed in the game as a whole. The first time you go for a dance, you'll end up banging a girl called Tami in the toilets; she'll subsequently hit you up for booty calls from time to time, (although this happens far less often than was the case with the girlfriends in GTA IV). One of your female colleagues at Maisonette 9 has a habit of calling you into her office for a "special reward", and several of the missions find Luis hammering away at some lucky lady's fairy garden. None of these sex scenes are particularly explicit, but it's unusual to see so many of them.

Surprisingly, the game doesn't make a big deal of its gay characters. Compared to the borderline cliché of GTA IV's Florian - who was nonetheless likeable - Tony himself is a restrained creation. He's a classic GTA screw-up who just happens to be gay. I'd hesitate to call TBoGT progressive, but it's still refreshing to see a game feature a normal homosexual character... well, as normal as a drug-addled corrupt club owner can be.

Unfortunately, Luis is a significantly less interesting protagonist than Niko, or even Johhny Klebitz. You warm to him with time, but he's never as engaging as the better characters in this episode: Tony, the excellent Yusuf, and Mori - the hyper-annoying brother of Brucie Kibbutz. Rockstar does its best to set up some tension between Luis' high-roller lifestyle and his past in Algonquin's housing projects, but we never care enough. It doesn't help that Luis' old homeboys, the dealer-duo Henrique and Armando, are an irritating pair of sods - although they do at least offer yet another set of decent side-missions based around drug wars. The most interesting aspect of Luis' character stems from his habit of sleeping with anything that moves. You'll eventually run into one of his troubled exes, a girl deeply hurt by Luis' cold rejection; if you pursue this plotline, you'll be rewarded with a particularly good cutscene that I won't spoil here.

You can work in Tony's clubs

Still, TBoGT's narrative arc is satisfying - especially in the many moments where Luis' path intersects with the adventures of Niko and Johnny. If you've played the previous two outings to Liberty City then you'll probably get quite nostalgic as you play this, and Rockstar has certainly done a grand job in wrapping up their epic storyline. Perhaps more importantly, the Scottish developer has finally implemented a system which allows players to re-visit missions they've finished. Once you've finished the main storyline, which should take you a good eight to 10 hours, you'll be able to go back to any past assignment you like. Each mission now has four secondary goals, ranging from completion times to a required number of headshots, and if you meet these targets you'll be able to compete against other gamers via the Rockstar Social Club.

There are other bonuses of course - more TV shows and tunes for the radio, and new multiplayer modes, including base-jumping competitions and tank-based high jinks. However, it's the mission design that remains the real star of this final add-on. I consider GTA IV to be one of the very best games of this console generation, but I know that many gamers felt let down by what they felt to be a lack of fun, following the carnival of insanity that was San Andreas on the PS2. Even if you were one of these people, you should seriously consider picking up TBoGT, as it features some of the most enjoyable moments of the entire series. In parallel with the superlative Chinatown Wars, The Ballad of Gay Tony restores a sense of playfulness to the GTA franchise, cementing Rockstar's status as King of the DLC.