For years it seemed as if no-one in Hollywood could make a successful pirates movie. Sure, if you looked back to the 1930s there was Errol Flynn in Captain Blood and a whole bunch of other swashbucklers - but in the second half of the Twentieth Century? Nothing but duds. From Roman Polanski's Pirates to Cutthroat Island, via numerous versions of Treasure Island, no-one managed to nail the formula, to deliver the quintessential pirate blockbuster. There seemed to be no hope for the genre... and then along came Gore Verbinski with Pirates of the Caribbean. It tore up the box office, won millions of fans and reinvigorated Johnny Depp's career. Jack Sparrow became a global icon: go to any fancy dress party and you'll find someone who looks like Russell Brand on a killing spree... only without the suspect trouser stains.

Why do I say all this? Because Rockstar's Red Dead Redemption is the Pirates of the Caribbean of cowboy games.

It's true. We've had a few decent rootin' tootin' howdy-em-ups over the years - Gun, Call of Juarez, the original Red Dead Revolver - but none of these efforts ever felt like the genuine article. Perhaps more importantly, from an industry perspective at least, they never seemed to win the heart of the gaming public. With the release of Red Dead Redemption I think things are going to change. The words "Grand Theft Auto" may be absent from the title, but Rockstar's pedigree is well known even among non-gamers - and on top of that, the release is being backed by a massive marketing campaign. More pertinently, the game itself is absolutely spectacular.

The sheer quality of Red Dead Redemption is evident right from the word go. After a moody intro sequence, former outlaw John Marston steps off a steam train and into the dusty town of Armadillo. Within seconds of the player assuming control, a drunk staggers out of the local saloon and falls flat on his face. In the grand scheme of things it's a tiny, insignificant moment, but to a certain extent it says a lot about the game as a whole. It's a nice little detail for starters, one that recalls the flavour and tone of countless Western movies. On a more technical level, it's also beautifully animated. It might seem strange for me to enthuse about a digital drunkard falling over, but when the guy tumbles to the dirt, it just feels right. This is a game where people fall over a lot, usually just after you've put a bullet or three between their eyes, and stuff like this matters.

A lot of people are probably wondering whether Red Dead Redemption is simply GTA IV with horses and funny hats. There's some truth to this idea: for all the improvements to the engine and game design - and there are many - the basic framework is very familiar. There's the usual downtrodden protagonist - a violent but principled underdog, surrounded by thugs and oddball scoundrels. There are the quest-dispensing NPCs, laden with dodgy-sounding promises, and there's the near limitless array of side quests and distractions. Once again there's also a huge open world playground to explore, but this time it really is open.

Since 2008, GTA IV's Liberty City has been the high water mark for sandbox game environments. The combined plains of Red Dead Redemption's New Austin and Mexico form a very different world, but there's no denying that they trump their urban predecessor on several fronts. Your surroundings are astonishingly beautiful at times, and when you ride to the top of a high crest of land you may find yourself pausing for a moment just to admire the sweeping grandeur of it all - the forests, deserts and canyons, and the pockets of human presence: a wooden shanty town in the distance, or a lone steam train crawling across the horizon. John Marston may be the (anti)hero of the story, but there's no doubt that the world itself is the star of the show.

As a result of the emphasis on travel and exploration, there are times when you feel as if you're playing a cowboy cousin of Fallout 3 or perhaps Fable 2. Hints of RPG have been creeping into the GTA series for some time now, and here the feeling of genre-blending is even more pronounced. As you ride from place to place you'll frequently run into other travellers, and if you pause to meet them these encounters will usually turn into an impromptu mini-quest (help the lawmen capture a missing prisoner; rescue someone from a lynch mob) or in what essentially amounts to a random battle. Even if the action doesn't find you, there's plenty of stuff to occupy yourself with: animals to hunt and skin, wild horses to be caught and tamed and cryptic treasure maps that consist of simple hand-drawn sketches depicting notable bits of scenery.

In town there are yet more distractions: as you progress through your adventures people will start to recognise you, and before long you'll have people openly challenging you to duels in the street. At the less violent end of the spectrum there are gambling opportunities - arm-wrestling contests, blackjack and a very decent simulation of Texas Hold 'em, to name but a few. If you manage to find yourself an elegant suit to wear, you can also cheat at some of these games - but if you do, you may wind up in hot water. There's something particularly satisfying about cheating, getting caught, and then blowing away your enraged rival after he's challenged you to a gunfight in the street. Each of these mini-games has their own simple set of mechanics, and they all work extremely fluidly.

When you're not engaged in some form of mission or activity - legal or otherwise - you'll probably be travelling from A to B. The horse-steering controls take a bit of getting used to, since your mount behaves like an autonomous creature rather than, say, a car with legs. Handbrake turns don't exist in this world, and instead you have to learn to anticipate where you want your beast to go next, slowing your horse well before encountering any sharp changes of direction. At the same time, there's a neat system that requires the player to monitor their horse's stamina: spur her too hard and she'll whinney and grumble; keep pushing, and she'll eventually buck you off. On the other hand, the longer you remain with one horse the closer your in-game bond will grow, boosting the animal's stamina.

In all probability, you'll find a similar bond developing in real life. In GTA IV you changed cars every five minutes or so, but here I ended up sticking with the same horse throughout the entire game - I grew that attached to the caramel nag I caught and tamed in the wild. By tapping up on the d-pad you can magically call your horse to your current location, and at times I would jeopardise a mission by pausing to swap from a beast I'd been forced to use to my loyal and trusty Binky (an unusual name, I know, but it stuck).

Speaking of missions, you'll notice that I've barely mentioned the campaign so far. This is partly due to the fact that I don't want to go into spoilers, but it's also because, for me, I initially found the stuff surrounding the campaign to be more interesting than the central narrative. Over time, this faded and I got deeply sucked into Marston's plight, but I'll admit that initially I found the story to be a bit slow. In the game's defence, the plot is clearly intended to work this way: in the beginning Marston is a stranger to us, reluctant to confide his situation even to the most helpful of NPCs, but eventually the truth begins to seep out - and as the story builds, so too does the weight behind the major plot beats.

If you were annoyed by the structure of GTA IV, whereby every NPC seemed to offer Niko help - but only after three or four missions of dogsbodying - you may find a similar sense of frustration with Red Dead. Stick with it: the characters you meet are excellently drawn, as a rule, and brilliantly voiced without exception. The over-arching story, meanwhile, takes its cues from several classic Westerns - particularly Sam Peckinpah's The Wild Bunch - but it also finds a powerful tone of its own. Be warned, however, that it's just as bleak as GTA IV, perhaps even a little darker. Personally, I lap this stuff up - and besides, what did you want from a Western? This isn't Blazing Saddles, you know.

The barebones campaign can be completed in about 15 hours or so, but in practice it'll be almost impossible to stick to the story without being led astray by some form of distraction - and really you should take your time to investigate every deviation from the straight and narrow path. Mission design is generally of a very high standard, though I occasionally got the sense that too many quests descended into a prolonged battle against an endless stream of bandits or some other enemy. That's not to say that shooting people isn't fun: gunplay feels beefy and satisfying, and a distinct improvement over GTA IV. There's also a very useful bullet-time system, Dead Eye, that comes in handy when the going gets tough in the later stages of the story. Again, the Euphoria physics engine has a big hand in making the combat work, and I dare say that the game sets a new standard for the art of making virtual men slump into a broken, blood-stained heap.

So yes, the action rocks bells. But I still can't help but feel that, for me, it's the less familiar elements that help to make Red Dead Redemption the best game of 2010 thus far. There's an early mission where you have to herd cattle with your horse in the middle of a storm, and if you cock things up you'll have to watch as the cows plunge over a cliff to their deaths. It's very, very odd - and yet even this failure feels remarkably fresh. At other times it's just the rich atmosphere that wins you over - a random encounter with a laudanum addicted girl in the wilderness, or even just the feeling you get as you ride across the land in the pissing rain.

On top of all this, there's also the ripe promise of multiplayer. It feels a bit cruel to relegate such a big slice of the game to a fleeting mention - that much-hated journalistic cliché of the "multiplayer paragraph at the end" - but unfortunately I don't have any other option. I've not had a chance to try out the final review build, but I did get to try a preview build a few weeks ago, and it had an awful lot of promise - allowing up to 16 players to ride and fight across the entire world, or to take part in team-based and free-for-all contests. GTA IV's multiplayer managed to carve out a strong user base, and if Red Dead sells the four million copies analysts expect it to by the end of the summer, then history may well repeat itself.

Only time will tell, of course. Perhaps I'm wrong, and the gaming masses don't want to rush out and embrace Red Dead Redemption in the way they did with GTA IV. If they don't, it'll be a crying shame and perhaps the final proof that cowboy games just don't work. But I don't think that's going to happen. I think this game is going to do the business, big time. I certainly hope it does, because to be frank, it's a magnificent piece of work that everybody should play. John Marston may not quite be the next Jack Sparrow, but in the realm of cowboy games, Red Dead Redemption is clearly the genuine article.