I think the song goes like this.... *inhales*

Turn-based? So I can't choose Ultima Underworld? D:

I'll have to go with Super Mario RPG as well. I still haven't completed it!

Same.Super Mario RPG it's very hard to complete without a guide or something.

...Why can't it be turn-based? Hack-n-slashes and the like are just as difficult.

The hardest RPG I've ever played was Fire Emblem: Shadow Dragon. I'm actually still trying to complete it. It's not terribly hard, but since it's got some completely new features than the previous FEs in the US (which I've played/beaten) it's tougher than the others.

Touhou labyrinth.
THIS IS THE HARDEST GAME EVER I KID YOU NOT. For those who know of the touhou series its meant to be difficult right? Well, touhou labyrinth is a fanmade project that took years to make. It was a touhou RPG game. However they made it RIDICULOUSLY tough. It is hair rippingly tough. .-. A cookie for who ever beat it.

You guys think that SMRPG is really that hard? It's quite straight-forward for an RPG. Grinding is really minimal in this game, if you do every encounter you see, which isn't grinding if you ask me.

I have to put two down on mine. Dragon Quest Monsters: Joker, and Dragon Quest VIII: Journey of the Cursed King. DQM is hard in the fact that you have to train 3 monsters, recruit better ones, fuse the better ones to get even better ones, etc. It also needs a little bit of grinding, as do most of the Dragon Quest games. DQVIII is a bit more on the difficult side. Grinding is definitely needed, and the post-game stuff needs an insane amount of grinding just to beat it, so you can say you 100% the game.

The entire MOTHER series. I mean, the enemies are overpowered and the bosses are over-rated and Super Powerful. But it makes up for that with hilarity and adventure.
And Super Maio RPG is not THAT hard. I mean, I beat it easily with no help. Just get some good equipment and items. And then it's easy.