Hi Finiko, I'll give you some feedback, hope you don't mind!
I would say this is a nice take on a breakout style game (also, the graphics fit well): even if it has mechanics from that game, it feels different enough because of the things you added, like the enemies and red crystals. By the way, just a minor thing, I could not really understand what were they: if the enemies are the nightmares as I assume, what are the crystals? But this didn't affect the gameplay, I think. Also, the context you made (protecting the world dreams) sure is welcome.
That said, In my opinion the game has the following flaw: it gets too hard too fast! To say the truth, I simply couldn't defeat the boss and see how time was used haha. Maybe it's because the gamespace is small, or the enemies appear to fast and the balls change direction fast, or I can't manage hitting all the balls that appear. I think making the space bigger (at least in height) would fix this issue. Again, this is just my opinion, and either way, good job making this one!