Ball Slider: Fill Box Puzzle comes from Xingming Huang.  The object is to slide all the balls until they hit a wall or into an empty space.
I solved about 60 levels in roughly 30 minutes.  After doing 3 or 4 levels, there is an ad.  Usually the 5 second type.
This game is strictly for beginning puzzlers who need to build some confidence.  Doing the last 25 levels I was curious: could I play it badly so that there would be a position that could not be solved" The answer is no!  Which means this game's main purpose is to generate ad revenue.
https://apps.apple.com/us/app/ball-slider-fill-box-puzzle/id1542183253

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