The Circle Pad Pro, which launched in Japan this month, is coming to the United States on February 7. The attachment snaps in around the base of the Nintendo 3DS, and includes an extra shoulder button as well. It requires a AAA battery to operate.
Here’s the issue: Existing games won’t work with the Circle Pad Pro, and developers will have to design future games to support dual sticks. So far, Metal Gear Solid: Snake Eater 3D and Resident Evil: Revelations are on the roster of supported games.