I recently finished Natsu-Mon: 20th Century Summer Kid, an action-adventure game with social/life simulation elements. It really left a profound mark on me, emotionally. It's about a fourth-grader spending his summer in the countryside, and it ended up making me feel very nostalgic. I got pretty bummed when it was over.
It got me thinking: what are some games that made you feel similarly? What games have stuck with you months or years after you've completed them, and why?