The Ghost of RubangB on 14 November 2009
Online multiplayer is for multiple people who already own the game to play together. This doesn't help Nintendo.
Local multiplayer is for groups of 4 people to play when only 1 owns the game. This way that person converts 3 friends into Marioboys. Those 3 Marioboys convert 9 other Marioboys, who convert 27 other Marioboys. This game will sell more than anything. It will be a viral word-of-mouth monster of epic proportions.
