I have thought of a few directions that I can do with the creation of the visual look of the game and the sound and music that could be used with it.
I have thought of a design idea which is to make sound and design of the game work together. This means that with the simplistic visual design of the game, there will also be a simple music and sound library that will be used. This would be pretty simple to program into the game as all that needs to be created would be the music for the game, and basic code which allows the music to player and to be muted if the player wishes.
Another idea is due to the simplistic visual design of the game, I could use a powerful score (music) to make the game have more emotion and identity. This will require more programming as different events in the game could make the music more powerful or weaker. As an example, the music might be soft when the player is small, but the music could become more powerful as the player gets larger. The problem with this idea is that this would require a lot of sound programming to make this work well, and the creation of multiple parts of a song that gets played depending on player mass (player size).
Final idea is to make different music for different coloured backgrounds for the game. As an example, you could have a more powerful song play when the background is red, and have a calmer song play when the background is blue. This would require some more advance programming and the creation of multiple songs.
I may add to this list depending if I think of more ideas.
Before I create any of the music for this game, or decide on which direction I want to go with this idea, I want to do some research into sound design for games, so that I have a clear idea of what I need to do to make the music work well with the game, and make the user like the game with its music, or even make the music as a way of a user to remember the game.