Changed your opinion

What is a videogame that changed your opinion about it's genre?

I'm not one to change opinion often, even along decades. That also goes for games, hardly anything has strayed that far from my expectations.

But I'll admit The Sims series - almost a genre of their own or you could talk about "casual sandbox" gaming beyond genres - was something I very much looked down before trying it. And by "trying" I mean two month frenzy of making over hundred elaborate houses and a breeding program that'd put Mendel to shame.