Dude, this is so cool!
It's really heartwarming to meet fellow designer of a arkanoid-like sidescroller! Just played your game, it feels nice. I wanted to implement mouse control long time ago but postponed it for too long, doing it now ;)
The controls suffer from some lag, or is that the intention?
Definitely not. It was laggy in fullscreen because I went too far with decorative background shaders. Patched this just now. It should run now as fast as the monitor allows.
Do you also make bricks with more lives?
Yes, in my game brick HP is proportional to its size and also every color has its own base HP.
How did you come up with the sidescroller idea? I recently learned that's not obvious choice :) For me, it mostly was because of one of my childhood memories, when I saw an older boy playing a sideways breakout in my school on a computer I didn't have access to. It looked incredibly cool! Now I can't even find out what that computer was, and can't find the original game either. But I kinda wanted to play it since then