Thanks! You would not believe it, but I made up some quick numbers for particle count and chaining target for each lvl and found them mostly ok. Tuning difficulty was just a matter of choosing the maximum radius and the amount of frames a circle would stay in that maximum radius. I completed it twice to check it was ok. I was afraid it was too easy. Now I realize lvl 7 is the most difficult lvl. After that lvl it's easy to sustain a big chain reaction due to the high number of particles in screen.
Btw, your game is great. You always get a level of playability and polishment that is impossible for us mortals 😅