Nice Game!
I have some feedback:
- add controls at start of the game and make them fade after a few seconds
- make the asteroids a little transparent or darker to give a sense that they're not on the same layer and they wont hit the players
also, if you plan to make them hit the player too that would make it harder and fun as well maybe in a difficulty or next stage, but i think the player speed need to increase or their speed decreased
^^