Mine is Lady Sia for GBA. It's just a platformer but I just love it played and completed more 20 times. Will probably speedrun it in future.
Look, I was born in the 80s, I played Morrowind about the time it was released (closer to GOTY edition, but whatever), but even I have to kinda agree with your niece at this point.
Though its gameplay and world-building certainly aged better than Oblivion's.