Bowser's Galaxy Generator is the final galaxy of World 6 in Super Mario Galaxy 2. In this galaxy, Mario, Yoshi, and Luigi use everything they got during the game to enter the final battle with the Koopa King himself. This is where the final Grand Star is hidden in this galaxy. To enter this galaxy, the player needs to collect at least 70 Power Stars. Once you have 70 of them, then the real final battle begins! Once you get the last Grand Star, then World S will appear after the credits and if 120 Power Stars are collected, then Green Power Stars will appear in all of the galaxies.