It's fair to say that this summer has been outstanding for those who don't mind the confusing currency conversion of Microsoft points. While people who are more tanned than I spend their days outside, the games industry typically slows to an absolute crawl as it stocks up on the best titles (and a few cash-ins, of course) for the Christmas rush. This doesn't occur in the world of Xbox Live Arcade, and you don't even need to brave the sun's rays to get to the shops. It really is a great service for those of us who find the beach an unlikely source of entertainment. With the brilliant Braid and Geometry Wars 2 already hallowing Microsoft's download service in recent weeks, Castle Crashers, an old-school-style cooperative beat-'em up that's been many years in the making, finally joins their ranks. Is it up there with the best of them? Absolutely.

For those not familiar with the likes of Golden Axe, Double Dragon and Streets of Rage, what you get with Castle Crashers is a 2-D side-scroller, where up to four players progress along linear levels by beating the hell out of anyone who comes their way. If that doesn't sound especially cerebral as I write it, then I've done my job because it really isn't — and the toilet humor that accompanies it implies that your hours spent on Brain Age will be of no use here. That doesn't mean it's not enjoyable, though, and Castle Crashers is an absolute hoot, especially when played with friends. You play one of four knights (distinguishable only by the color you select) on an initially clichéd adventure to save a number of princesses who have been kidnapped. Using a range of medieval weaponry, you take on a diverse set of enemies from hooded thieves and armored knights all the way up to giant water-bound cats and space aliens. Despite the story's clichéd beginnings, it doesn't stick to the rules.

You have a number of attacks, combos blocks and magic spells in your arsenal (though it can become too easy to rely on the latter as you progress) to take down colorful enemies, with the traditional boss fight every few levels. A modicum of depth is added with RPG-lite elements: You level up as you progress, and you can improve your attack, defense, agility and magic skills. The RPG-lite elements actually blend in really well, and if you're playing with friends, it's possible to balance your team in a very effective manner, and this, along with some time and reaction-based levels, prevents the game from ever feeling too repetitive. It's certainly not a small game; in addition to these hidden extras, the 36 levels will take you between six and 10 hours to plough through, which makes the price of 1,200 Microsoft points ($15) seem less exorbitant. You can feel that Castle Crashers is truly a labor of love and easily one of the strongest games the XBLA service has yet presented.

The real charm is with the multiplayer, and while there's nothing that will stop a determined player from completing it on his own, he'd be missing out on a hell of a lot of fun along the way. There's even a little extra competition thrown into proceedings, as upon rescuing each of the four princesses, the players are required to turn on each other in a brawl to see who earns the cartoon princess's kiss. Little touches like this make Castle Crashers a multiplayer experience, and while the game may be pushing its price point when played alone, it's more than covered if you have the friends to support it. The good news for those without such acquaintances in close proximity is that the developers have added Xbox Live play for up to four players. The bad news is that it currently is far from perfect; drop-outs are common, and it's very hard to get a game running for more than a few minutes. On the bright side, a patch is on the way, so this shouldn't stop any players from taking the plunge once Microsoft gives the update the all-clear.

This solid communal entertainment is backed up by an excellent presentation throughout. The graphics are charming hand-drawn cartoons, which look wonderfully crisp and full of character through the Xbox's high-definition output. Despite being simple in its presentation, the game manages a lot of comic detail within its animations, varied colorful backdrops and character models, and it's the art style that will stay with you when you look back on Castle Crashers in years to come. Although its over-the-top violence means that there's oodles of cartoon blood (though it's no worse than your average Tom and Jerry cartoon), this is a delightful contrast to the kind of muddy browns and grays that occupy the majority of the console's postapocalyptic death-obsessed titles, thus continuing the game's quest to breathe a whole lung capacity's worth of fresh air into the XBLA lineup.

Likewise, the music is also spot-on, with a mixture of cheery rhythms more commonly associated with first-party Nintendo titles. They're extremely catchy, despite their throwaway nature, and they fit the mood perfectly. If there's one area completely without fault, it's Castle Crashers' presentation.

The truth is that it's hard to find fault anywhere in the package. Indeed, the only area that Castle Crashers struggles is the extra content they've tried to (battering) ram in. There's a mini-game called "All You Can Quaff" that can be played online or on your own, but after a single playthrough, I can't imagine why anyone would want to. The premise is for your knight to eat through as much medieval food as possible by repeatedly ramming your fingers against the controller's face buttons. It's exactly as much fun as it sounds, and I can only assume it was included for the joke with its title. Regardless, I'd be struggling to choose between admiration and pity for anyone who manages to pick up the 20 gamer points for winning 20 of these battles online.

If you've never liked side-scrolling brawlers in the vein of Golden Axe and Double Dragon, then feel free to move on because the neat little additions and charming art style of Castle Crashers will do nothing to win you over. If your eyes fill with tears of nostalgia at their very mention, though, then don't be put off by the price of 1,200 MS points because it's worth every penny if you have the friends with whom to enjoy it. The demo will tell you everything you need to know, so if you like that, you'll love the finished product. Castle Crashers has been a long time in the making, but truly worth it: It's one of the strongest downloads on XBLA and a genuine labor of love.

Score: 8.5/10