This game really isn't very good at all. Nice idea though.
Things you could imrpove:
1)Make the red ones EASIER to hit. This might actually make the game hard.
2)Make the space ships shoot at you.
3)More level variaty.
4)Add special effects.
5)Make more Red ones drop than blue ones, or make the red ones take off more score. Trust me, it helps.
6)I don't like blocks for space ships and stuff, put a little bit more effort into them. (I'll help you on this if you really can't sprite.)
Do those few improvements and the game might actually be playable.
I liked the stary background how-ever, good job on that. I'm also glad you didn't use TGF sound and music, nor Windows buttons. :)
(In fact the game would be better if you switched the blue blocks to the red blocks. ;)