Thanks for trying out this game and for the feedback too. I have updated the game and now it uses space bar to fire and move. I also implemented the hold to fire thing. So now you can hold space and the player will keep firing at a steady rate. The only use of mouse will be to control the direction of spacecraft. I also tried to make the difficulty curve more smooth.
As for the feedback upon taking hit, I am still working on that. I wanted to add a camera shake for that. But no luck so far. 😅