Mario takes to the skies and beyond in another outing to save the Princess. As the Mushroom Kingdom prepares to celebrate the arrival of a comet that appears in the skies every hundred years, Princess Peach sends Mario an invitation to attend. As Mario arrives, Bowser and minions attack the Kingdom and once again kidnap the Princess... and her entire castle. Mario gives chase but is lost as the ship leaves the atmosphere and ends up on a space station built on the visiting comet overseen by the mysterious Rosalina. It's up to Mario to brave new galaxies, find the elusive Power Stars, and bring his friends home.

Super Mario Galaxy plays similarly to Super Mario 64, as Mario explores his latest 3D world defying gravity, crossing various terrains, and even running upside down across the planet surfaces. Bouncing from planet to planet, Mario must collect Star Bits and coins, using his usual jump attacks and spins (now controlled with movement from the Wii Remote). The Wii Remote is also used to collect out-of-reach Star Bits and also can be controlled by a second player.

In addition, Mario can find new suits (similar to Super Mario Bros. 3) that give him the ability to turn into the ghostly Boo Mario, the high-flying Bee Mario, launch fireballs as Fire Mario and skate across frozen lakes as Ice Mario. New challenges also await Mario including ray surfing, balancing on a high-speed ball, floating inside bubbles, and other challenges in his quest to get all 120 stars. Even Luigi lends a hand in the search, making valuable contributions to the adventure.

Players can also take a snapshot of the worlds they've completed along with their best record times and send them to their friends via Wi-Fi.