Super Mario Galaxy: Grand Quest is a game for the Wii U.
Mario has been invited to the star festival along with some friends. Mario is about to see Peach but bowser sets the castle on fire and launches Peach and Mario into Space. Then, Mario finds himself on a giant starship shaped like a read and green and purple Luma. then he sees Lubba, Polari, Toad Brigade, and 3 Yellow Lumas.
His first mission is "Dippy Piranha's Ground Pounds". after fighting bosses and achiever every star, Lubba will say that the Purple comet has appeared and is in some of the Galaxies causing you to go over some galaxies.
After that you will have to battle bowser for the last time and he drops a giant grand star. when that is done, open your file and you can play as luigi, peach, or Rosalina.
each galaxy has 4 power stars, 2 comets, and 1 hidden star (some have green stars).