Really cool concept and progression !
I really like the way you introduced the different particles slowly so that you can get the time to grasp each new mechanic before tackling the more challenging puzzles, the slowdown is super cool and really useful to plan precisely where a particle will hit.
And i also like how you essentially seem to have taken inspiration from puzzle bobble type games for your aim/shoot mechanics and spun it in an entirely original direction, also the Ui design is pretty clean and clear, and i like that your main menu selection essentially sorta serves as a mini tutorial since you have to aim and shoot the button you want to select.
If i had to nitpick i'd say the only issue i had is that i didn't understood right away the target's cover mechanic where you need to have a certain charge level for it to open and let you hit the target, but that's really no big issue in the end since it's easy to figure out through trial and error ^^
Well done :)