Super Mario Galaxy is a 2007 platform video game for the Wii, and the third 3D game in Nintendo's Super Mario series. As Mario or Luigi, the player embarks on a quest to rescue Princess Peach, save the universe from Bowser, and collect 121 Power Stars. The levels in the game consist of galaxies filled with minor planets and worlds, with different variations of gravity, the central element of gameplay. The player controls the player character using the Wii Remote and Nunchuk, and completes missions, fights bosses, and reaches certain areas to collect Power Stars. Certain levels use the motion-based Wii Remote functions.