A game doesn't have to be brave to be great. Mario Kart 7 is about embellishments rather than radical innovations, refinement over restructuring. That's not to say it's lacking in ideas - on the contrary, it introduces a number of creative tweaks that build upon the weaponised racing formula established in the 1992 original without compromising its inherent simplicity. One or two additions may be little more than throwaway gimmicks, but no matter. This is a brilliantly designed video game in its own right, and perhaps the most comprehensive and well-balanced Mario Kart to date.

Its signature new feature, as made clear by the misleadingly bland boxart, is the glider that unfolds from each kart as you take to the skies. Instead of merely allowing you to enjoy the scenery - though that's a pleasant side-effect of this in-flight entertainment - you have a number of choices while airborne. You could swoop down quickly, accelerating all the while to hit the ground running, or remain airborne a little longer, collecting coins (more on those later) and scoping out alternative routes - like veering right to hit the rooftop boost strips on Daisy Hills, for example. It's surprising how much they add to the experience, to the point where you'll miss them on the flatter tracks.

Underwater racing is not quite as interesting, slowing the action down slightly - which the sluggish 50cc mode really doesn't need. Otherwise it's entirely harmless, merely allowing you to misjudge the odd jump or corner and avoid Lakitu having to fish you out. He still carries a rod to rescue you from lava and fatal plunges into the track-side abyss, mind.

Yet the presence of these aquatic sections does help to vary the level design in what are among the most interesting new Mario Kart tracks in a long time. Most are themed after Nintendo characters, from the Middle East market streets of Shy Guy Bazaar to the delicate glaciers of Rosalina's Ice World. All are packed with shortcuts and alternative routes, some of which are accessible through judicious use of mushrooms, and others merely by veering off the beaten track at the right time. Often you'll spot a route only when you're past the entrance, and make a mental note to find it on the next lap, only to struggle to locate it: one or two are extremely well-hidden and the very best shortcuts require precision driving to negotiate - a strip of narrow boost platforms on Wuhu Island being a case in point.

Yes, the world's blandest holiday destination is here for two tracks and a battle mode arena, but credit to Nintendo EAD for finally making the resort an interesting place to visit, if only because you're whizzing through it at high speed. Wuhu also heralds a new approach to track design - rather than laps, both courses are one long strip, split into three distinct sections of track. The same goes for a gorgeous new take on Rainbow Road, which sees you fly off the multicoloured ribbon of track and onto a bouncy, cratered moon, via the rings of a Saturn-like planet and a string of floating star portals. Other traditions are rather unnecessarily upheld: the new DK Jungle and Bowser's Castle environments are among the least interesting tracks. Next to Koopa City - a rain-lashed, frost-blue futuristic environment - they feel relatively bland.

Thankfully, they're a rare exception. Each course is full of delightful touches, from the kart-triggered tones that sound as you arc around the giant piano, xylophone and glockenspiel of Melody Motorway, to the Wii Sports Resort theme fading behind the sound of the wind rippling your glider wings on the vertiginous descent from Wuhu's Mount Tenganamanga. Elsewhere you'll see Mario Galaxy's penguins racing beneath the ice, tiny Bonefins swimming toward the camera, and Olimar's spaceship parked beside Rainbow Road. And you can immediately tell when a new track has an underwater section, because Lakitu will start the race wearing a snorkel.

The 16 new courses are accompanied by an equal number of golden oldies, re-imagined, appropriately enough, by Retro Studios. Most have had a visual overhaul, and all have been gently tweaked to fit the new vehicles. There's some lovely restoration work on the part of the Texas-based team here, and the touch-ups only enhance their appeal. Besides a couple of strange choices - N64 Kalimari desert is a dull old track - it offers a solid selection picked from the previous six Karts. The GameCube's Daisy Cruiser is especially welcome, while the whirling neon lights of Waluigi Pinball are one of the visual highlights, particularly with the slider up.

In fact, it's perhaps the most technically accomplished 3DS release to date, the action running at 60fps even in 3D. The image depth is fairly subtle for the most part, making it comfortable on the eyes, and the small screen's sharper edges help Mario Kart 7 pip its Wii counterpart to the chequered flag as the best-looking Mario Kart yet.

But is it the best-playing? Nintendo puts forward a strong case. Coins are back, marginally increasing your kart's top speed as you collect up to a maximum of ten, the right kind of encouragement to take a riskier racing line. Snaking is out, as drift boosts are based on how sharply you corner, with red sparks reserved for the tightest of turns. Rubberbanding is either much less obvious than before, or entirely nonexistent; it does mean 50cc is a bit of a procession once you take the lead, although the dreaded blue shells attempt to keep it competitive. It's noticeable, however, that they only usually arrive when you're comfortably ahead. And if you're overtaken as a result, nine times out of ten the next power-up you collect will be a potentially decisive red shell.

New weapons include the Tanooki Tail - and boy, is Nintendo getting its money worth from that art asset - which whips opponents and wards off incoming projectiles for a short time. The Fire Flower is also temporary, causing minor spins for opponents, though its bouncy trajectory is a little erratic. The Lucky 7, meanwhile, is a collection of seven different power-ups that circle your kart, and it's absolutely fascinating. It only arrives when you're struggling and while it initially seems overpowered, obtaining it can easily cause a loss of focus as the burden of choice literally whirls in front of your eyes. Any collision at this point will cause you to drop items, which can be fatal when you lose a Bob-omb that's primed to explode, making the Lucky 7 empowering yet nerve-wracking. Despite these new additions, weapons feel less pervasive than in Mario Kart Wii and Double Dash!!, shifting the focus back towards the racing. If the action remains chaotic on 150cc mode, that's only because the AI racers are stronger and more able to keep pace.

As your cumulative coin tally reaches certain milestones, you'll unlock new kart parts, allowing a greater degree of customisation than usual. New tyres, chassis, and glider wings are available, all of which will impact your vehicle stats, the latter less severely than the others. Changes can mitigate character weaknesses - a Toad-driven monster-truck offers a much greater top speed than his default kart - but there's always a compromise somewhere, whether it's a heftier vehicle that handles as clumsily as a shopping trolley with one duff wheel, or slick tyres that slow you to a near-standstill should your backend edge off the tarmac during a drift.

The other notable new single-player addition is a first-person perspective that allows you to steer with the gyroscope as well as the circle pad. However, it's little more than a brief novelty: it's eminently controllable, and demonstrates a more obvious visual depth, but most will revert to the standard behind-kart view after half a lap.

Plenty for the solo player to chew on, then, but the most substantial improvements are reserved for the game's online component. You can compete against random players across the world, or choose a race to join from those on your friends list, as well as a handful of recent opponents listed underneath. The new Community feature is the biggest change, allowing you to create up to eight different setups, each with a name and icon, and a series of settings to suit a group's particular tastes. Whether you fancy a Balloon Battle with Bob-ombs as the sole power-up or a sedate 50cc race sans items, there's an option to suit (almost) everyone. This might not be the most revolutionary idea ever, but for Nintendo it's a bolder step into online waters, even if it then shoots itself in the foot somewhat by giving you a 14-digit code to share with friends by way of an invite - leaving you to decide the method of delivery.

It can take a while to find players to race against, though this should be less of an issue when the game goes on retail release. Once you've found a suitable match - based on a rating that aims to pair you with similarly-skilled players, and which fluctuates depending on your online performances - you may have to wait a short time for a race to be finished before you can start. The wait is usually worth it: races are smooth and lag-free from turbo start to frantic finish.

Local play, meanwhile, allows one cart to support up to eight players, with the option to add newcomers to your friends list by simply tapping an icon, an unusually progressive move for Nintendo. Those who don't own the game are forced to race as Shy Guy, though downloading the data to compete doesn't take too long. Indeed, the small multiplayer game is more fun than it's been for a long time, perhaps since Mario Kart 64. Of the new arenas for the two Battle modes, Honeybee House is the weak link, its honeycomb of interlinked rooms proving a little too restrictive. Wuhu Town is an improvement, with a network of narrow streets surrounding a more open circular centre. Sherbet Rink is easily the pick of the bunch, a slippery sheet of ice with rubbery bumpers that makes for a welcome dose of chaotic karting slapstick, while the three older tracks - Super Circuit's Battle Course, MK64's Big Donut, and Palm Shore DS - provide reliable backup. Find a regularly available group of pals (either online or off) and these modes could potentially keep you going for months. And if they're busy, the time trials - with ghosts available via Streetpass and Spotpass - are more than adequate compensation.

Mark Rein suggests Super Mario 3D Land has a case for being 3DS's killer-app, but as brilliant as EAD Tokyo's platformer is, Mario Kart 7 is a more comprehensive realisation of the capabilities of Nintendo's much-maligned handheld. It's not brave, it's not innovative, but neither should it be casually dismissed as 'more of the same'. That winning formula has been prodded and poked and buffed until it gleams, leaving us with a game that is, at the very least, the finest Mario Kart since the original. For some, it might be even more than that.