Smack - The Puzzle Game comes from Ai Ayatsuji. The object is to slide the balls along the grid to knock out other balls. If you can end up with only 1 ball, you've won.

This game is extremely similar to Fling!  Long term Loyal Blog Followers will remember this from 2010 when I first reviewed it.
I even posted an update.

So I just redownloaded Fling!  Smack is okay, but the graphics are just nowhere near as good as Fling!  Both games are free.
https://itunes.apple.com/us/app/smack-the-puzzle-game/id1447871235"mt=8

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