What are some games that are legitimately hard? Not pseudo-hard (commonly thought to be "hard" but in actuality aren't). Preferably oldschool games but list any you like. Only requirement is they actually be legitimately hard to even the best of pros.
Examples of pseudo-hard games. (These easy games are frequently thought to be hard by less experienced gamers who haven't tasted true difficulty yet). Contra, Super-C, Super Mario Bros. 3, Super Mario World, Super Punch-Out!!, Marble Madness, Mega Man, Mega Man 2, Mega Man 3, Super Mario Bros: The Lost Levels, Donkey Kong Country, etc...
Examples of overrated hard games. (These games are hard but are very far from the hardest games out there but are frequently incorrectly cited as "hardest games of all time". Games with respectable difficulties). Battletoads, Castlevania, Zelda II: The Adventures of Link, Legend of Zelda, Legendary Wings, etc...
Examples of truly hard games. (These are games that can kick the butts of even the best of the best even for people who've beaten them before and generally can beat pretty hard games. Less than the hardest of hardcore gamers need not apply). Abadox, Snake Rattle 'n Roll, Adventure Island, Air Fortress, Double Dragon III: The Sacred Stones, Star Tropics, Teenage Mutant Ninja Turtles
Format can be like that, where you can list pseudo-hard, overrated hard, and truly hard if you like.