Super Mario Galaxy 2 is the most unnecessary Mario game of all time.
That might be why it is one of the best.
Galaxy 2 has an easy mission, because, for once, it is a Mario game without a big mission. It is not launching a new gaming console, as did Super Mario Bros., Super Mario World and Super Mario 64. It is not trying to prove greatness can be at last succeeded, as the long-awaited Super Mario Sunshine had to do in the shadow of '64. It doesn't have to prove that weird concepts like spherical levels or baby Mario or four-player Mario can carry a Nintendo action-adventure to sunny heights. It doesn't even have to satiate Mario-starved fans, because those fans are probably still plump with the last big Mario adventure, which was released not six years ago but six months ago. It doesn't have to help its home platform become a hit, because the Wii already is one.