Nintendo didn't even mention the 3DS's second Circle Pad attachment at its pre-Tokyo Game Show (it never attends the show) 3DS conference last night. But sure enough, a tiny blurb popped up on its Japanese site pricing, dating and listing the games that will support the expansion attachment.

Let's get right down to business. The "Expansion Slide Pad," as it's officially known will be released on December 10 in Japan for about $20 (1,500 yen) and will require one AAA battery to power it.

It will not be a one-off thing that's made only for Capcom's Monster Hunter 3 (tri) G game as previously thought. It'll also be used by Ace Combat 3D Cross Rumble, Dynasty Warriors VS, Kingdom Hearts 3D: Dream Drop Distance, Metal Gear Solid Snake Eater 3D and Resident Evil: Revelations.

As Gamepro points out, all of the games using the Expansion Slide Pad are made by third-parties. It remains to be seen whether Nintendo itself will support it with titles like Mario.

The quiet release of information regarding the add-on suggests Nintendo isn't ready to tout it, for fear of backlash by the already unsteady 3DS population. Or, the add-on was created simply to appease third-party developers who might see the PS Vita as more enticing to make games for.

Whatever the reason, it's almost certain that the games themselves will not mandate the use of the Expansion Slide Pad, unless the games come with the accessory bundled in. There's also the matter of fairness in multiplayer modes. Will those who have the Expansion Slide Pad have an advantage over those players who choose not to use it?

Nintendo has some explaining to do.

Via Gamepro