I believe this might have been made in Scratch.

Was a bit unclear of what to do at first, but soon figured it out.  I think this is an interesting concept, that can be improved with some more feedback to the user.  For example, when the black ball disappears after a certain amount of time, there's no difference in its exit than when it hits the ball.  Maybe like an explosion or something when it hits the red ball would help, and maybe like an extra point when the black ball disappears on its own.  Nice concept!

the mechanic is very good! You have something good here!

In terms of originality, this is great! Just add more gameplay to it and improve graphics and this can be a really great game!

Fun fact, endurance games like this one is actually a genre.

I recommend you add a difficulty curve if you want to continue working on it.

Firstly I did not get now to get score , then mid way i figured it out by my self . You could add some tutorial or simply some text . By the way how is the theme implemented in your game