The "Terrain" sprite is the ground it is necessary. Feel free to redesign the ground but use the same rectangle used for the dirt of the ground as to retain a somewhat smooth look. The "Clouds" sprite is simply the clouds it runs on a pretty basic code and can be removed. The "Background" sprite is just a background. It serves no purpose except it works well with the clouds and it is easier to copy it over as a sprite. The "Start Button" is a placeholder for the begin signal