Hi, congrats on your game! :) The gameplay mechanics are simple but well executed. One point I would criticize is perhaps representing the crystals more clearly to the player. It took me about three crystals until I accidentally collided with the fourth to realized they were CRYSTALS instead of enemies haha xD
If you have some spare time, please try out my game. It's a classic space shooter from the 80s but with a personal touch. Please leave your honest feedback.