Cool game! I once worked on a prototype similar to this except the goal was to drop the blocks in such a way that an AI controlled character could climb the blocks to safety. The blocks were always sinking into water so you tried to keep placing blocks so that the climber could keep climbing forever.
Your idea is more interesting)))
And I want to say thank you. Your game Flying Aces help me to find solution to work with sound loops in Godot.
You use a creative hack, in order to engine sound loops. I tryed the same, but this hack has own limitations. And than I understand, what was wrong. Whan game starts, Godot drops the set_loop_format option to 0 (do not know why). Then I just neet to set it in _ready to