Mario & Luigi: Bowser's Inside Story

You know what? After years of resisting it, I'm going to give in. I'm done rescuing princesses and ducking Bullet Bills. I've finally embraced my inner Bowser, and I couldn't be happier. Crushing stuff underfoot, burning things with flaming breath: why was I missing out on this for so long? I may even write a self-help book on the subject.

Bowser's Inside Story (the title doesn't refer to the Mushroom Kingdom's answer to Panorama, unfortunately) isn't the first time you've been allowed to play as Mario's oddly lovable foe, but it's both the most gimmicky and the most thorough opportunity you're ever likely to enjoy. Through the course of a 20-hour narrative, you'll get to know the boss of the Koopa Troopas inside out, exploring everything from Rump Command to the Nose Deck, learning to appreciate all aspects of his tortured and rather complex personality: the constant stream of sniggering asides (it's a cry for help), his minion-motivating skills, and the way he barrels through enemies and fragile landmarks with the mildest shove of his gigantic paw.

And the truth? It feels pretty good to be Bowser, thanks. After years of picking a path carefully around threats, jumping out of harm's way, and tackling challengers mostly from above, it's a pleasure to put those cares aside and relish a few hours of spiky, tortoise-shelled power.

Mario and Luigi haven't been forgotten, of course, but they spend a large part of this surprisingly deep RPG - the sequel to Partners in Time and the GBA's luminously cuddly Superstar Saga - creeping around unmentionable locations within the rubbery inner spaces of their greatest nemesis, sparking nerve endings to life, unblocking arteries and hitting strange nodules with hammers. Inside Story retains the fairytale simplicity of the previous games' plotting, but there's a new layer of gunk-tank ickiness to proceedings that sits surprisingly well with Alphadream's more self-aware take on the Mushroom Kingdom.

It starts, rather topically, with a nasty epidemic: everyone's coming down with the blorbs, a mysterious virus that causes them to swell to five times their normal size and roll around helplessly. Mario and Luigi are called in to investigate, but before they can get to the lab and start first-stage drug trials and double-blind placebo tests, they're swallowed up by Bowser, who's been drugged with a poisoned mushroom by series regular Fawful, causing him to inhale half the local population. From deep within their old enemy's internal organs, it's up to our heroes to power Bowser back up again with some rudimentary hands-on surgery, before taking the fight to Fawful and returning everything to normal.

Granted, there aren't many game franchises which would choose to take you inside one of the cast members for a sequel - if Halo: Colon Evolved was ever kicked around at Microsoft, it must have been at the end of a very long day, in which an awful lot of red-ringed 360s got sent back to the office - but Inside Story manages to pull the whole thing off effortlessly. It builds the rather disgusting premise into a clean-lined RPG, switching back and forth between Bowser's fairly brutal approach to exploring the over-world with the unfortunate plumbers' puzzle-heavy adventures, mostly located within his body.

It's a winning blend of game styles, but the show-stopping moments come when you need to co-ordinate between the two plotlines, filling Bowser with water, say, to open free-floating doors within his intestines for Mario and Luigi to slip through, or manipulating the monster's muscles from the inside so that he can lift boulders or bust open new locations. In other words, it's Zelda: A Link to the Past with a questionable medical degree.