Awesome twist, but no basics.
This is a very good twist on the mouse avoider genre. The ability to stop and be invincible but inactive is a really cool idea that I would love to see implemented in a game with a little more meat to it. Of course, there lies the problem in that this game doesn't.
Each level a few more balls are added, the safe zone shrinks a little bit and that's it. No real advancement and no end in sight. Where are the other kind of enemy balls that behave differently? Where are the power ups? Where are all the basic elements of a really spectacular mouse avoider?
Like I said, you've got a truly unique, innovative and enjoyable twist on the genre but unfortunately you lack all the basics to make it a good game. I'd recommend adding in a few more features (and a definitive level progression) and you'd wind up with a real winner on your hands.
By the way, were the balls supposed to be magnetic? They definitely behaved that way what with the sticking together and sling-shotting off of each other...