Fun little game and really cool idea. I found it cool that sometimes there weren't enough rocks to destroy all the ships so you have to push some of the ships back while you wait for more rocks, good job! Also I invite you to play my game it you have the time :D

Very fun  and innovative!

Fun game. Reminds me a lot of Asteroids.

The mechanic is really interesting, but it did feel like the alien to asteroid ratio wasn't always right, and there were times where I was shot without any asteroids on the screen to use. This might just be a skill issue on my part, but if you were to work on this more, maybe if the asteroids are hit by a laser, they could break into smaller asteroids which would even out the ratio a bit? This could give the player more options for how to use the asteroids, since there would be more incentive to use them like shields.