A nice implementation of the classic formula! I like the addition of the onscreen buttons for mobile support, that was a nice touch!. The colors you chose work really nicely with this type of game.
I do feel like the game speed is a little bit quick, could it be that the simulation speed is tied to the framerate? It is really difficult to pass the first level currently the enemies shoot and descent very very quickly. (or maybe I'm just very bad at the game haha)
Nice submission!