What are some games that you didn't expect would be fun but actually are?

A big one for me is FFX. The whole game is basically just a bunch of corridors taking you through the story on a rail like Splash Mountain, and yet when I play I can't stop and I just have a blast. I still have no idea why it's so fun to me.

I just find it unusual because with most games - even "So bad it's good" games like EDF 2017 - I can pinpoint exactly why I find it fun. But I really can't tell you why I enjoy FFX so much.

How about you?

P.S. inb4 this turns into some sort of rehashed debate about FFX/Tidus/etc. That's not the point of the thread