Apparently in the 1980s, some boffins at Capcom came up with an arcade machine that had two screens.
So some other boffins at Capcom started developing a dual screen game called Dark Void.
But then some of Capcom's other other boffins canned the arcade machine and so the whole project was cancelled.
How however, Dark Void is resurrected.
Of course, there's a big single screen version being made for consoles - go figure - and also a little version, called Dark Void Zero, which brings the side-scrolling shooter action of the original to DSiWare.
You can see what they all play like in the following video.
Dark Void Zero is due to be released in the US DSi Shop in January. We'd expect the European version in January too, but Capcom hasn't said anything officially yet.