Waltzing Tiles comes from Boris Sokolsky. The object is to slide the rows/columns back/forth and up/down to un-mix the colors.

The easy mode is way too easy. We've seen this type of puzzle way too often.

The medium mode is slightly harder. Each tile has either 3 or 4 colors.

The hard mode is fantastic.  And very hard. As you slide a row across, each tile rotates 90 degrees. So there are 2 tasks: solving for the position of each tile and the orientation.  I've tried it only once and ran out of moves. 
https://itunes.apple.com/us/app/waltzing-tiles/id1315369332"mt=8

https://sites.google.com/site/waltzingtiles/

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