Very interesting concept. However, I am wondering, what exactly are the criteria to make the background character happy? Is it more random like in real life or do you actually draw your conclusions only from music theory and the impact of intervals on the listener? For me, sometimes simply playing the scale made the person happy, whereas elaborate melodies made the person sad...
At first, I could not access all the notes: The lower C was not playing. Turns out, the instruction "Play the notes with the bottom row of the keyboard" only applies for QWERTY keyboards. If one is using a different layout, one has to press the letters "Z", "X", "C", "V", "B", "N", "M" wherever they are located on the keyboard.