I enjoy a good brain teaser app.

I have found these to share: Free Flow and Flow Fit (there are a total of 5 with these names)
They are no cost and provide a daily as well as a collection of puzzles that (i feel) help me start my day with a quick brain teaser.
So if you like to untangle fishing line or truly to figure out that old bicycle lock combo from 10 years ago (

no they are not really that bad), you may like these.