It seems no one thought that porting a 2D game to stereoscopic 3D would be a problem… Using NES Shooter Xevias as an example, Nintendo’s Takao Nakano explains the perils of these previously unforeseen difficulties: “With a 2D screen, players had to use their imagination for Solvalou flying above the ground, but on the Nintendo 3DS system, we thought we might be able to recreate it using stereoscopic graphics so it looked like it was really floating. In the original version, the game unfolds on a flat surface. The moment we made Solvalou float in midair, all sorts of discrepancies arose. For example, when an enemy on the ground fired at Solvalou in the original, everything was on the same plane, so it didn’t seem unusual if the bomb appeared at the same altitude as Solvalou the moment it was fired and then hit Solvalou right away. But with the Nintendo 3DS system, Solvalou is floating in midair. If the bomb suddenly appears – zhing! – at the same altitude as Solvalou… We were like, ‘Huh? Something doesn’t feel right!’ Everything was off!”
“At first it looked like you would merely port it, but it actually turned out to be a lot of work! I would guess it was about 20 times the work of merely porting it.” It seems that to cope with the dimensional difficulties, some games will require a complete graphical overhaul. Hence the limited amount of 3DS Classics available…
Thanks to CVG for the info.