Really nice idea !
The audio effects and graphics are nice, the gravity simulation is good.

You probably have some issues with the sounds because when i played the sounds for the destruction of asteroids sometimes stopped playing.

The lasers are a bit unfair when they spawn close to you and you don't have time to react, you could probably improve that by tweaking the randomization a bit.

Nice game, I really like the concept of gravitating around the black hole ! And I like how you have to "protect" the black hole to be able to destroy it. There's a cool concept with the movements/thrusters with gravitation as well