The concept of this game is not to shabby, but the execution is poor.
[Here a couple problems that I have with this game:]
~ Upon opening this game in a tab, it just "starts". There is no initial menu. It's instant death.
~ The coins have little no value. There is no shop nor upgrades. If they were meant to be, purely, your score, you should have implemented a high score bar.
~ There is no enemy warning or indication.
~ It's very short. (I've played many short games such as ones in the ludum dare category, but that's the point of them, and they're we're so well done, in my opinion, that they didn't need more content to be great; They left me wanting more.