Star Ball Rolling
From the Super Mario Wiki
“Hey, now! If you're thinking about just rolling that ball away, you'd better listen to old Bill Board here. If anything gets in your way, smoosh it! Anyway, you'll learn more by doing it yourself. Good luck!”
Star Ball Rolling is one of the four minigames in Super Mario Galaxy, along with Bob-omb Blasting, Bubble Blowing, and Manta Ray Surfing. Mario rides on a Star Ball, which is, as the name implies, a ball with a Power Star inside. The goal is to roll the ball past multiple obstacles, including wandering enemies and voids, and into a hole to break the sphere and obtain the star. Mario must avoid all hazards in the stage to successfully reach the end and clear the minigame. The player can play this minigame in the Rolling Green Galaxy, the Melty Molten Galaxy, and the Rolling Gizmo Galaxy. Whenever Mario hops on the Star Ball and begins to roll around on it, the tempo of the background music changes as Mario either moves around or stays still on it. It is hard to roll the ball and if he rolls out of the edge he fall into space.
The minigame is once again playable in Super Mario Galaxy 2, in the Rolling Masterpiece Galaxy and the Rolling Coaster Galaxy. It is one of the three minigames in this game along with Crate Burning and Fluzzard Gliding. However, there are now two different balls that the player can roll on, the aforementioned Star Ball, and the new Purple Coin Ball, which appears only in the Rolling Coaster Galaxy. Additionally, the Co-Star Luma can stop the ball from moving.
The player controls the Star Ball by tilting the (held upright) in the direction they want to go. If the player is going very fast by tilting the remote all the way in one direction, it will be difficult to stop the ball, which could result in losing a life. The player can also jump while on the Star Ball, which can be used to change their direction quickly or cross small gaps if enough speed is built up beforehand. Finally, the player can crush any enemies in their way by rolling over them with the Star Ball.