NanaOn-Sha's Masaya Matsuura has said that developers in Japan are beginning to question the longevity of the DS format and its appeal to a gaming audience.
The respected Japanese developer observed that the younger consumer is very conservative when it comes to new software, and that titles aimed at a more mature market are not having the impact they did when the format first launched in the region.
"Some people have said already that the DS software's bubble has burst," commented Matsuura to Gamasutra.
"We have to keep increasing the chance to make more unique titles, but for us it's getting much more difficult because the game market - especially in Japan - is still very conservative.
"Many people know that the DS has very unique titles, like Brain Training, or something like that, but it's not for younger-aged market. It's kind of older people, like me."
With multiple developers and publishers jumping on the bandwagon to create 'training' style games, Matsuura said that sales of such titles have inevitably tanked.
"[One company I know has] some kind of learning type of game. The first one sold over 200,000, but the second one is 8,000. So these kind of things are going to happen," he said.