Blue Donut comes from Just So.  It came up in the search of new puzzles on the app store.  

The object is to rotate and swivel up/down/around the gold figure in order to release the blue rings.
I solved 30 levels in about 10 minutes.  As a puzzle: this is for kids. But in terms of design and programming, it's elegant.

Deleting it now.
https://apps.apple.com/us/app/blue-donut/id1471914434

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