Super Mario Galaxy 2 is a platform video game developed and published by Nintendo for the Wii. It was first announced at E3 2009 and is the sequel to 2007's Super Mario Galaxy. It was released worldwide in 2010. The story follows Mario as he pursues the Koopa King, Bowser, into outer space, where he has imprisoned Princess Peach and taken control of the universe using Power Stars and Grand Stars. Mario must travel across various galaxies to recover the Power Stars in order to travel to the center of the universe and rescue Princess Peach.
The game was originally planned as an updated version of Super Mario Galaxy; this version would have been called Super Mario Galaxy More. It was later decided that the game was to be developed as a fleshed-out sequel when the development staff continued to build upon the game with dozens of new ideas, and so development time expanded to two and a half years. Among the additions are dynamic environments, new power-ups, and the ability to ride Yoshi.
Upon release, Super Mario Galaxy 2 was met with widespread critical acclaim, and is regarded by many to be one of the greatest video games of all time, as well as one of the highest rated video games on review aggregator websites. It is one of the best-selling games on the Wii with over seven million copies sold worldwide.