At the core of the Wii's appeal is its motion-control interface. It gives the gamer a feeling of immersion in the game while inviting casual gamers who may not have the patience to learn an advanced controller a reason to pick it up and give it a try. In fact, Nintendo sold more than 3 million consoles in the United States alone in 2009. Worldwide, customers bought more Wiis (9,594,000) than both Xbox 360 (4,770,700) and PlayStation 3 consoles (4,334,600) combined. [source: NPD].
Knowing this, Nintendo released an updated version of its motion controller. Actually, it's more of an add-on. Nintendo's Wii MotionPlus accessory snaps into the same socket as the Nunchuk and, according to the company, it translates game players' actions into game movements in a 1:1 ratio [source: Nintendo]. Wii MotionPlus formally released with Nintendo's "Wii Sports Resort" in July 2009. While older games can't take advantage of the improved control offered by the add-on, some titles released afterward require the functionality the device offers [source: Bakalar].
"Wii Sports Resort" is the popular follow-up to Nintendo's most popular game "Wii Sports." Game play and graphics are similar, but Nintendo created new games that are designed to take advantage of the Wii MotionPlus attachment. The bundle costs $49 or you can buy the MotionPlus attachment separately for $19.