For me it was Okami. I remember you do a ton of shit to get to a certain boss which I thought it was the end, only for it to reveal that there was a loooong path ahead.
Other than that, maybe cyberpunk? I was surprised after all that stuff you do in the beginning just to see the titles pop up
Honestly, Final Fantasy.
I was 5 or 6 when I first played it in 90, and I had no idea how long a game like that was supposed to be. So when I beat Garland and the bridge was built to the rest of the map, I was in awe.