I really like the tone of this - there's a relaxing summer evening feel to it for me with the people resting on the riverbank and the look of the fireworks display.
Gameplay is simple and effective, and felt at its most fun when there were a load of fireworks onscreen all detonating simultaneously :)
Audio feedback is simple, but surprisingly encouraging and relaxing with multiple arpeggios playing at once. Really worked well with the overall feeling the game creates.
If you were to develop this further, would be great to see some kind of incentive not to press keys that weren't currently required - found it quite easy to cheat by pressing all keys at once