Super Mario Galaxy

Overview

Each Nintendo console has it's own Mario 'series', with the Super Mario Bros. Trilogy on NES, the World series on the SNES, the Land series on the Game Boy, and the 3D Mario games, with  Mario 64 on N64, Sunshine on Gamecube, and Galaxy on Wii.
 
The Galaxy series is the first 3D Mario series to have a sequel, and the first Mario series to have a sequel since Yoshi's Island became the sequel to Super Mario World.
The Galaxy series involves the gameplay from Mario 64, but on spherical worlds with their own gravity. Platforming using these factors is what makes up the game design for the series.  

In the Galaxy series, Mario needs to collect 484 Power Stars, the highest number in any Mario series from various galaxies like the Rightside Down Galaxy, Bowser's Galaxy Reactor, Bowser's Galaxy Generator, and more!   

Music

The music for these two games are performed by the Mario Galaxy Orchestra, a special orchestra designed for these two games. So, the Galaxy series has three soundtracks. The first two are from the original game and comes in two versions, the normal one-disc version, and the two-disc platinum version with 81 songs. For Super Mario Galaxy 2, an official soundtrack was released on July 10, 2010. It has two discs and 70 new songs. So altogether, that makes a grand total of 151 songs that the orchestra performed in these two games.