So, like, my own personal experience...

A couple of years ago I applied for a certain company that this year turned out to be a unicorn.

The automated reply said to build a Minesweeper. So I did. It took a several hours to get into a shape that is playable. Then it took several days to polish it into app store quality.

You can play here: http://www.ronilan.com/bugsweeper/

Download here: http://www.appstore.com/bugsweepergame

And copy as much as you want from here: http://www.ronilan.com/bugsweeper/js/bugsweeper.js

If you are wondering how it went from there, they were "evasive". Then I got a softball "center a div" interview with one of their front-ends. Then I got a polite no thanks from the recruiter.

And that's all I have to say about it.