You could get into Dragon Quest games, if you want old school JRPGs. Complexity might be a bit lacking given the era, but doing the old NES ones without a guide is excruciatingly difficult and you can lump on RetroAchevements to add more pain. RA generally adds additional challenges to any older game so you have to play a little min maxing to accomplish them.

I mostly thought of it since RA is beta testing multi sets with DQ9 and getting every accolade might be one of the most insane things I could ever suggest.