Thanks Alberto!

I'm glad you enjoyed it You've come up with some good ideas too, that would definitely improve the game's enjoyability. I like the asteroid idea - maybe they could travel a bit faster than the space invaders, and also require perhaps 2 hits to destroy. They could appear only in later levels to add some variety. I also very much like the stars idea, as that would not only improve the visuals, but also give a much needed sense of perspective and help the player better judge where their shot is going to go. At the moment it is quite difficult to work out unless you have played for a while.

Thanks again for trying it out and for the suggestions!

-Ben