The sequel to one of the most beloved games of all time, Super Mario Galaxy 2!
When it came out on May 23, 2010, this sequel added many new elements to the galaxy formula, like Yoshi and a level select screen rather than a hub-world. Some would see this game as unnecessary and inferior, due to less focus on plot, but it is still a galaxy Mario game at it's core.
Check out the awesome review by Matthewmatosis below! Note: that review belongs to him, not me.