Caelum displays a series of gameboards with a space theme. Your ball-launcher takes the appearance of a space-ship blaster, while the orbs look like your science-class representation of electrons, neutrons and protons. The board's background itself never seems to change (okay, they do change, but it is always some colorful nebula cloud, nothing too distinctive) and neither does the frame around the board. Overall, a lack of variety in the screen that you will see the most of is one of the reasons why the game quickly loses its novelty.
Between levels, a bit of text is displayed, which is supposed to be the blog of the robot piloting the space ship you are on, but the fact that this screen never changes and you see the same static images every time just adds to the overall humdrum feel.
Music continues that theme as there are only a few different background songs and only a couple of sound effects for when your ball hits an orb. These issues would only be slightly annoying if the same lack of variety wasn't carried out throughout the rest of the gameplay experience.