Nice puzzle game! One piece of feedback I have is to prevent multiples of the same sound effect at the same time. There's probably multiple ways you could implement this, but for instance you could have the AudioStreamPlayers be independent from the objects that make the sounds, rather having one as a child of the level which is called upon by all the objects that want to make that sound. The default for the max polyphony is 1, meaning that even when multiple of the same sound is called on the same frame, only one will play and it won't be louder than usual.