Why did Mario Party 8 see such a large increase from the Gamecube games?

[XiaoMay]

The game is not so good...

But it's a combination : there's expended audience, 1st one to use Wiimote, been a while since 7, no sequel right after it...
And it's not so bad overall. And dont forget no good game when it went out, Mario's in the name and install base.

MP9 should add online, Wii Speak, Balance and Wii Motion +... to do at last half these numbers !