"What is the Nintendo 3DS Circle Pad Pro?"
The Nintendo 3DS Slider Pad, also unofficially known as the Expansion Slide Pad and the Slider Pad, is an attachment that clips onto the Nintendo 3DS to add a right-side circle pad to the system, as well as a second R-trigger ("R2") button.
Nintendo confirmed the existence of the Circle Pad Pro at 2011's Tokyo Game Show.
"Why was the Circle Pad Pro developed?"
The Nintendo 3DS has one built-in circle pad on its left side. While this is sufficient for comfortably controlling 3D games like The Legend of Zelda: Ocarina of Time 3D and Star Fox 64 3D, most current-generation consoles are packed with controllers that feature two analogue sticks--one on the left, and one on the right. The right-hand stick is typically used to position the in-game camera wherever the player wants it, and we've become used to having that option.
The Nintendo 3DS Circle Pad Pro gives users more command over camera positioning, and, through the addition of the R2 button, allows for smoother interaction with 3DS games that have complex control schemes.
The PlayStation Vita, Sony's follow-up to the PlayStation Portable and a direct competitor to the Nintendo 3DS, has two built-in analogue sticks. Nintendo's Circle Pad Pro will help make things easier for developers who want to publish their games on both platforms.
"When will the Circle Pad Pro be released?"
The Circle Pad Pro was released in Japan on December 10, 2011, and will come to America on February 7, 2012.
"How much will the Circle Pad Pro cost?"
It will sell for $19.99 USD.
"Does the Circle Pad Pro need batteries to work?"
The Slider Pad requires one AAA battery to work.
"Is it coming to North America?"
Starting February 7, the Circle Pad Pro will be sold at American GameStop stores for $19.99 USD.
"Which games support the Circle Pad Pro?"
So far, we know that the following 3DS games support the Circle Pad:
Monster Hunter Tri-G
Biohazard Revelations (Called Resident Evil Revelations in North America)
Ace Combat 3D Rumble
Metal Gear Solid: Snake Eater 3D
Kingdom Hearts: Dream Drop Distance
Dynasty Warriors Vs.
"Is is necessary to have the Circle Pad Pro in order to play those games?"
Currently, it doesn't seem as if the Circle Pad Pro is mandatory to play any Nintendo 3DS game. It's meant to make certain 3D games a bit easier to control.