I've mentioned an old street-level superhero game I played 20 years ago on this thread already (which is preserved in a
Story Hour on this site). Looking back, I now suspect it was the tipping-point between "sim" and "nar" for me, and perhaps also for my GM.
It was a solo game, so there was room to get a LOT more into character backstory and development than would be fair in a game with more than one player. And I had in the back of my mind the idea of the samurai being on a collision course with bushido, of it being more or less expected the situation would come to a crisis.
So I created a character that was in a pressure cooker. The situation at the start of the game simply could not go on indefinitely the way it was - something would have to give at some point. I had no idea what! But I wanted to find out.
There were several aspects of that pressure, not just one. But probably the most explosive was the main character's relationship with his son on the one hand and his sidekick on the other. (Son doesn't know about sidekick, but sidekick does know about son - but hero doesn't know he knows! One reader described it as a "paternal love triangle"!)
Add the fact that the hero NEEDS his hero identity to let his bottled-up emotions out, and that he desperately NEEDS to believe that he's just an ordinary guy in his 'real life' - and thus NEEDS to keep son and sidekick in different compartments of his life - and you have a recipe for a truly glorious mess! I loved every second of it.
But we were playing it in Mutants & Masterminds 1e, which is a "sim" system. It chafed a bit. It captured the superhero action, but not the stuff I was actually interested in. When I encountered Fate a while later, I was hooked! (It may have helped that M&M 2e, which came out a couple years after we finished the game, took a surprisingly "nar" approach to character disadvantages! ie, when they cause an issue, you get a hero point, rather like a Fate compel. I loved the idea.)