On September 30th, Mastiff revealed that Gurumin 3D will be releasing to the North American Nintendo 3DS eShop on October 13th. It will cost .99, and until 10/31, a free 3DS theme will also be available to download.
Mastiff has confirmed that they will be revealing information regarding other regions soon.
I’ll have the release date and the theme deadline both added to the calendar.
— Gurumin (@Gurumin3D) October 1, 2016