Nice art-style and good concept! It became ridiculously easy if you just run clockwise and continuously renew mines at spawn points so it can be played forever, but it's absolutely excellent for the first game! My first game was just about staring in the window and listening to seemingly endless ambient music track. xD
Haha, its a good way to play! I think the difficulty ramp may be too gradual. It DOES get harder over time, up to a point. I think my high score is somewhere around 5,000?