The level design is prone to Mario-by-numbers retreads - genuinely inspired moments are outnumbered by familiar throwbacks. But let's face it, Nintendo's second-best is still better than anyone else's A-game, and you can hardly blame them for having perfected 2D platformers two decades ago. It's formulaic, but it's following a formula for sheer brilliance. You cannot fault New Super Mario Bros. Wii for variety, surprise, intricacy, freedom, tuning, pacing or sheer wealth of ideas.
Another significant improvement is to be found in the new power-ups. The DS game's novelty Mega Mario and underwhelming Blue Shell are gone, the superb Mini Mario returns - underused, if anything - and the classic Fire Flower is joined by the Ice Flower, whose snowballs freeze enemies in ice blocks that can be picked up and thrown, or used as platforms. The stars of the show, though, are the Propeller Suit (super-jump and float) and the Penguin Suit (better handling underwater and on ice, snowballs and a high-speed tummy-slide). Funny, foolishly adorable, wild and flexible, they've got all of the cartoon joy of the power-ups in Mario Bros. 3. Even better: Yoshi's back!
So are the wise additions of the wall-kick and ground-pound that New Super Mario Bros. brought over from the 3D Mario games. It ought to be redundant to mention the controls in a 2D Mario - they're tight, tactile, supple and intoxicating, of course they are - but it is a shame that some moves, notably the propeller jump and picking up some items, require you to shake the remote rather than press a button. It's quick and reliable enough not to let you down, but just awkward enough to break the telepathically instantaneous bond with Mario that you're used to. Other instances of motion control, such as tilting the remote to move certain platforms, are sparingly applied and good fun.
Played solo, New Super Mario Bros. Wii is an improvement on the DS game, but it has the same character. It's almost routine in its excellence, resting with ease on Mario's mountain of laurels: a brilliant game, but more tribute than true successor, and an exercise in deja vu for the seasoned Mario fan. With more than one player, however, it's transformed.
It's no more nor less than a chance to share the exuberant, mischievous joy of this magnificent series - and in doing so, to multiply it. The integration is invisible, and total. Up to four players can play through the entire game in the main mode, dropping in and out at any point. You can help or hinder each other as you feel like, but either way, the difficulty balances out perfectly. The tag-team element grants that many more chances to stay alive and keep the level scrolling, but the multiplication of bouncing, free-wheeling chaos sparks off chain reactions of cause and effect that often spiral out of control. When these end in disaster, though, it's always hilarious, slapstick disaster that's impossible to begrudge.
In addition, there are two dedicated multiplayer modes, Free Play and Coin Battle. Levels are unlocked in these as you work through the main game, but both also offer a recommended selection from across the game's eight worlds unlocked at the start. In Free Play you compete for score and enemy kills, displayed on a leaderboard at the end of a level, while Coin Battle is a pure hunt for the most coins. Both work superbly but the purity of Coin Battle wins out; it's a fantastically greedy scramble, even better in the five levels designed specially for it. The replay value added by these modes is immense, as if the hunt for every secret level and Star Coin in the main game wasn't enough.
It's a shame that you can't compete for score in the same way when playing in the game proper, but that's a structural quibble at best. The lack of online multiplayer is a tougher call, especially since it's available in the similar LittleBigPlanet, but maybe that comparison tells you all you need to know about why Nintendo didn't include it. Great though it is, Sony's game doesn't have anything like the same razor-sharp timing, the same busy complexity to the level design and interactions, the same raw speed. Lag might have thrown Mario a microsecond off perfection, and in this series, that would be unforgivable. Besides, New Super Mario Bros. Wii is such a great social game - not so much balanced between co-operation and competition as embracing them both in a rowdy, rough-and-tumble group hug, full of friendly rivalry but totally free of malice - it is absolutely worth gathering your friends together to play it.
Who knew that, locked in the time-honoured traditions of Super Mario Bros., one of the greatest co-op games ever was waiting to get out? Well, Shigeru Miyamoto did. In unleashing it, Nintendo hasn't moved its classic series forward one jot; it hasn't had to. But it has given it a riotous new lease of life.