Nintendo's twin-screen wonder has seen almost as many reinventions as Lady Gaga, so it may not come as a huge shock to hear that the DS (in all its guises) has now sold over 50 million units in the US. The home entertainment maestros are still chasing similar success for its three-dimensional sibling, the 3DS, however. Nintendo has managed to sell almost half a million three dee units units after its weighty price cut, but there's now some very potent competitors seeking their own slice of the (portable) gaming pie. Good luck, Nintendo, you're probably going to need it.