Hey there!
This was a fun game. The controls and rules are simple, which goes well with this type of games. I really have no complaint about the game mechanics.
Two suggestions if you ever plan to continue working on it:
1. Add a leaderboard: I think trying to beat that high score makes the game even more addictive, so a leaderboard might create more incentive for players. You can also record the player's own high score. This might be easier to implement.
2. I can also imagine playing this on the bus. So maybe you could consider creating a mobile version.
Overall, great game. Good job!