Once you start playing with sound, you will encounter some issues. Since we usually use midi-style music, we typically only need a few thousand bytes to make a good sound track. However, playing music that sounds good consumes a ton of processor time, so you cannot do anything that requires too much in the way of graphics. In most cases, unless you want to do beeps or if you have some sparse times when you play music, almost all processing power is devoted to the sound, and what remains is devoted to checking key presses so the user can exit or pause.
That being said, I have made a grayscale game before that played sounds (it was like an arcade game) :D