Reworking classic titles to support 3D as part of the Nintendo 3DS 3D Classics range has turned out to be a much more laborious task than originally hoped, Nintendo has said.

In the latest Iwata Asks feature, Takao Nakano, the director in charge of the 3D Classics series of games, told the Nintendo president that simple ports simply aren't possible.

"We based the 3D version on the arcade game," explained Nakano discussing the 3D Classics version of Namco Bandai's Xevious. "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."

He continued: "In the original version, the game unfolds on a flat surface. The moment we made Solvalou float in mid air, 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 mid air. If the bomb suddenly appears - zhing! - at the same altitude as Solvalou... We were like, "Huh? Something doesn't feel right!" (laughs) Everything was off!"

In the end, it was roughly 20 times the effort to bring the game to 3DS than performing a simple port, said Nakano.

Nakano and his team have already released Excitebike for 3D Classics and Xevious will be released in July. Four further titles are in development.

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