Picross 3D for DS was one of the titles announced by Nintendo at E3, but not dated or mentioned again, like Line Attack Heroes, Monado: The End of the World, and, until recently, WarioWare DIY. According to posts on Cubed3 and NeoGAF, the puzzler will be out on February 5 -- in Europe. Though Nintendo UK still lists the date as "TBA", Cubed3 reports that Nintendo has confirmed the February 5 date.
Picross 3D, developed by HAL Laboratory, is based on the familiar Picross puzzle, in which players make marks in squares based on clues about how many in each row or column should be numbered. But Picross 3D starts with cubes instead of squares, with each mark chipping away at the cube to reveal a voxel-based 3D object.
There is no release date, rumored or otherwise, for North America, though the game was announced for release here.