I love the idea and it's a really intuitive keyboard (Similar to garageband-type keyboard)
After playing a few tunes on it I feel like the main issue with this is the lack of a game. I really love everything else about it though. I love the artstyle, the visuals and the sound effects.
Another thing you might be able to add is a very soft pad in the background of every note so that there is a sense of genuine harmony and the overtones made by the drill sound can be ignored by the ears. This is more of an artistic choice, but I would have it this way.