Oh Mario, just when you thought it was safe to hang up your wrench and leave Princess Peach to her own wilfully damsel-in-distress-like adventures your Nintendo paymasters once more haul you back and put the weight of the gaming world on your shoulders.

The Wii U is in trouble - sales are not where Nintendo hoped (or even expected) they would be. But you certainly can't accuse the Nintendo big wigs of lacking optimism. 'Next year we'll sell 9 million Wii Us' is the forecast suggested after 3.4 million sales in the console's tricky post-launch months.

And what is this optimism based on? Yep - you guessed it. Mario.

Mario Kart

Mario Kart and Super Mario Bros. are both highlighted by Nintendo as software that will 'drive hardware momentum'.

When it comes to driving his Kart, Mario is definitely the man. But I'm not convinced that even this most iconic of gaming legends has the power to convince the doubting masses that the Wii U is the console for them.

In Nintendo's defence, another of its gaming stars - the Wii Fit - is also highlighted as on the way for Wii U, but this particular pony has already used its solitary trick when it rejuvenated the Wii. Whether it will work again is a long way from certain.

Even with Mario there is a law of diminishing returns. I grew up with Mario games, loved them and still use them as a touchstone of gaming in a simpler, more gleeful era.

Yet, every time Nintendo goes back to the Mario well, hoping that our affection for this plumber is bottomless, it feels like an air of desperation is creeping in. One of these days he's going to set off to rescue a damsel in distress and find out that Master Chief or Solid Snake has got there first.

Mario - in simpler times

Nintendo has earned itself a special place in gamers' hearts, and the well-timed and entirely necessary price drop for the 3DS means that it retains its place as the go-to portable gaming platform, but although the Wii gave it a whole new market of casual gamers, it left them precariously reliant on an audience that is less loyal, less likely to buy games and less driven by titles.

The Wii U is an obvious attempt to change that, to bring back that army of Mario-fans and Zelda-lovers, without sacrificing those nouvelle family gamers. Whether the console falls between two stools is probably not for me to judge, but the sales numbers will not be encouraging anyone at the company.

I genuinely hope I'm wrong - that the arrival of the most obvious white knight, a garishly dressed plumber with a jaunty cap, can prove to be the killer app for this generation's Nintendo.

But hovering ominously over the horizon is another Japanese great with a point to prove, Sony's PlayStation 4 and, of course, Microsoft's new Xbox. The core gamer - even a Nintendo stalwart - may well be looking at these consoles and wondering if they can abide leaving Mario on their 3DS and embracing a whole new set of core games.