While visually identical to its predecessor, Super Mario Galaxy 2 is actually a very different title, both in content, structure, and gameplay. Even the formula is similar--Bowser, King of the Koopas, invades the Mushroom Kingdom for the umpteenth time and kidnaps Princess Peach. Mario, initially helpless to do anything, gives chase as his archenemy flees into outer space, leading into a long journey across various worlds and planets.
True to the "Galaxy" moniker, Super Mario Galaxy 2's gameplay is largely founded on gravity, or rather, the manipulation of it. Depending on the size of a planet, Mario can jump far enough to break orbit, and in some case, use gravitational pulls to solve tricky puzzles.