The object is for the Pink Man to pick up the pink stars and the Green man to pick up the green stars etc. However: the Pink Man cannot travel on the pink squares. But when he travels over the green or blue squares, those squares become pink. Similar rules apply to the Green Man and the Blue Man.
There are only 40 levels, but that's perfect. I've solved all but 5 levels.
https://apps.apple.com/us/app/squares-impossible-puzzle/id1551995757