Rockstar has always been tight-lipped about its development plans, even if we all know they are busy shrimp, so broke they have a mysterious DS game is not surprising.
Systemlink reported that: they have a former employee of Rockstar resume, and the resume has never been published, revealed a DS game.
This name more than three years working in Rockstar’s AI programmer, referred to a “never declared the DS game”, it has a “full 3D open world” and “complex close combat system.” Rockstar has produced a DS game, the “bloody people @ Don @ Street”, but it does not have a “complex system of close combat.”
The employee was involved in “black Los Angeles’ development, and time is so long (this staff in October 2010 is gone), and perhaps this DS game has been canceled. However, we dare guess: maybe it is still under development, and the platform into 3DS.