I also learned a lot about English through games. The most notable was my very first game, Xargon. I could barely read at that point and didn't have any idea what the textboxes said. So I tried to decipher the words and make sense of it, just from what they sounded like, or what the showed scenes and pictures suggested was happening. Oddly enough, I came really close at times. So when I finally learned English at school, it already felt familiar and I didn't have problems with "complicated" words that the other students frowned upon.
My native language + vocabulary also benefitted from the legacy of Kain series, especially Soul Reaver. The translation is just gorgeous. It also helped with general storytelling.
Freelancer taught me about planets, suns and the universe and got me interested in it. You can scan pretty much everything for statistical and historical data. At the age of 11, I already knew about neutron stars, red giants and white dwarfs, as well as modding for some time. At that time, I learned more about programming than I ever learned at school.
The Witcher: Basics of sword-fighting, at least in theory, as well as knowledge about demons and other monsters in folklore.
Devil May Cry: Again, demons and spirits of real-life folklore. Not very useful, but nevertheless interesting. You'll constantly see some of those in fiction.
RPGs and games about certain eras can often be a good way to learn about different epochs, even if they take a lot of liberties.