Apple wants to emphasize the fact that 2016 is a leap year, so it's created a new app sale for iOS. As a consequence, five highly-rated apps for the company's mobile operating system are now free. If you get all of them, you save $15. The main caveat is that this deal is only available today - since February 29 is a day that only exists every four years and all that.
Bridge Constructor and Super Sharp are games, while Spark Camera is obviously a camera app. Sketches+ lets you create drawings and take notes, and Windy is all about white noise sounds that calm your mind. You can find all of these in the iTunes App Store, naturally.