I am still quite new to Construct 2 and love it! The things it can do amaze me.
Yes, it has highly customized projectiles. The projectile behaviour can be applied to all kinds of things you never imagined to create awesome effects.
There is no built in "level-up" system, unless I miss-understand what you mean. But all the hooks are there to easily build something like that.
Same with "unlock/achievement" system. C2 is a lower level development tool - you would have to define and build your own system, but it wouldn't be that hard.
Randomization is certainly posible, but again, you would have considerable work defining all the parameters to make sure it would still be functional.
You can do almost anything imaginable with particles.
My 13 year old son, with no prior programming experience, has been creating things that blow my mind! (It does help that he has a programmer dad to help out when he gets stuck though).