Although the main use cases are (as you've rightly guessed) games and social media, there are a couple of other amazing use cases I've seen appear.
The most common is to use HIVE and (more frequently) HBD as a medium of exchange. It's still very early days, but Hive is popular in Latin America and especially in Venezuela. In and around the city of Cumana, there has been a drive to persuade local businesses to accept payment in HBD. As with all things Hive, it's the effort by individuals driving the project, and I'd like to give a special shout-out to @edmundochauran along with others who have put a huge amount of work into this.
The other inspiring use case I've seen (although I can't find a link to it right now) is that Hive is using HBD to fund the building of a couple of wells in Africa to provide clean water to people in a very water-limited area.
Although it's not strictly a use case, Hive members in various countries periodically have face-to-face social meet-ups. So while it doesn't directly use HIVE or HBD, without the existence of the blockchain, those friendships wouldn't exist.
I'm sure there are plenty of other use cases which people far more knowledgeable than I will be able to add !