If I understand right, it seems that “serious” games isn’t quite the moniker you'd want to use. It seems more along the lines of games that promote a specific type of social consciousness or bring awareness to an agenda or point of view.
Interestingly enough, most of these games are freely available on the web (or sponsored by donations anyway), in so far as there would be virtually no market for them otherwise. They typically tend to be fairly simple and heavily biased towards the author(s) personal opinions on the subject at hand.
Well one of the most famous examples would probably be
Super Columbine Massacre RPG. A lot of people hold this game in contempt for it's subject matter but it's a very interesting project designed to question the whole moral stewpot around that tragic event.
The Marriage is more of a "games as art" project, but it has some overlap in this genre of "agenda" games. It's meant to be played with no knowledge at all and serves as a digital metaphor for marriage.
The ReDistricting Game is another interesting example which puts players in the role of gerrymandering an area to play to your political parties strengths.
And you might be able to even make a case for
America's Army given it's backstory. While, for the most part, it plays like a straight up FPS, it is designed around propaganda with the sole focus of military recruitment. It's also pretty fun and actually had a retail(ish) release which makes it quite unique.
Let me know if I'm off base with these suggestions. It's an interesting "side" genre of video games that's just now getting some play in the media at large. I'm assuming your patron is collecting this data for a research paper of some type. I'd be interested in seeing the final product.