The CES challenge seems interesting, but I imagine you'd have to combine it with some restrictions to keep the difficulty up -- those three are basically the backbone to my games without levels or magic, so one can only imagine what they'd be like with both.

Level 1 FF9 is a ride, man. It's almost fine until you hit that tree and the black mages start dropping in and your head explodes. > .<

Also, Final Fantasy V Ancient Cave is a blast if you like that game's mechanics, which basically everyone does. There's also an FF6 Ancient Cave, but I don't think it is as good, especially since it is random who gets Shadow's 'leave after random battles' flag, and life is kiiiiiiiiiiiiiiiiiiiiind of hot garbage when Terra dips out on you.