Language.
Empathy. (Let's just say, being alone when you grow up leaves you "lacking" in certain things.)
Emotional growth. (While yes, it's another word for Empathy, this one specifically refers to recognizing MY emotion and reading other people's emotion.)
Learning basic common sense. (Different parts of the world, have different cultural norm. Learning what's "normal" in other places help me understand other people that comes from different places.)
Strategy. (I usually play games that has RPG mechanics, and next to that was Strategy. I'm not very good at thinking ahead of stuff, still not to this very day in fact, but games like these help me re-arrange my erratic thoughts.)
Anger management. (I've got a lot of thoughts running through my head, and majority of them isn't very positive. The games I've played allows me to relieve my stress while simultaneously taught me to solve problems WITHOUT hitting them first.)
My life, for a lack of a better word to describe it, is pathetic. Despite my current addiction to video games, it was better than the alternative.
And trust me, I've seen the effect it has on other people. I've lived through it myself. It wasn't very nice. Depression is a hell of a mental disease.
I'm not doing optimally, but it's certainly better than before! And I have video games to thank for that. It saved me from boredom, depression and help build me to be the person I am today!