Ruan Shilong has created an interesting set of maze-type-roll the ball puzzles. The object is to roll the balls until an obstacle has been reached and then get to an exit.
We've seen this type of puzzle app game many times before. Here's what's interesting: most of the levels have multiple balls to exit. As soon as 1 ball goes through an exit, that exit becomes walled-off. So the real puzzle lies in figuring out which ball should use which exit. Also, you will want to minimize the number of moves.
There are 30 levels in each grid size. I did 10 in the 6x6 grid and 2 in the 9x9 grid.
I like this set of puzzles. If you've never played this type of game before, give this a shot.