For several years, once a week, the editorial office App Store selected one of the popular paid applications of any category and offered to download it for free. The 100% discount was valid for seven days, had no restrictions and was updated every Thursday. You've probably already paid attention to the past tense. The fact is that since mid-September Apple I stopped giving away applications for free.
The new App Store introduced in iOS 11 has a 'Today' tab that shows the app of the day. However, this does not mean at all that if the application is paid, then it will receive at least a small discount. In contrast, the prices for paid apps in this section remain the same. The same goes for the 'Game of the Day' section – every day there is simply a new page dedicated to one of the games.
In iOS 11, efforts Apple were aimed at making it easier and more convenient for users to find the application they like. Giveaway for games and apps had lower priorities. Of course, there is always the possibility that the 'App of the Week' section will return to App Store, but this is unlikely to be expected anytime soon.