That original Ninja Turtles game for NES (still the hardest game ever)
Spot on with that. Was so much fun, but so damn hard. Mike and Raph were basically useless so once you lost Don and Leo you had no chance.
I never got anywhere on Zelda:Ocarina of Time(more through lack of trying to) or Zelda 2:The Adventures of Link.
Another massively hard game was Battle of Olympus on the NES.