Seen things like this before.
yes, you could say that many people have posted games onto newgrounds like this lots of times, but you have created a slightly moddifed verison, theres a few inprovements you could make such as making the wall colours change or are much more depth instead of a fake 3d feel, the shadow on the ball dose not react with walls, but it could be quite hard to do, the ball its self is quite plane and you could of put some shading on it, the music loop gets quite anyoing after a while, also the box inwhich you have to hit it in isnt central (unless u wanted it to be of slightly) u could move it around to give the game an edge, you could put some SFX to lift it up a bit create more intressting for the user.