Actually, coming from the arcade era, NES games were freakin' easy.

Older arcade games were evil.  They just got faster and faster, bigger and bigger, and went on and on forever until they crushed your soul.  You didn't win those games.  The game owned you.  Sure you got a high score, but there was no light at the end of the tunnel except the score and bragging rights.

Most gamers crushed SMB3.  Had you called it difficult back in the late 80s/early 90s, people would have laughed at you.

OP, have you tried Yoshi's challenge for SMB2 on the GBA? Has anyone beaten that while keeping their sanity?

 True, most of the dam level isn't that bad but the seaweed part is infuriating. If you don't buy into that, I'll up the ante to level three of Battletoads.

Can I offer Beetlejuice? Nowhere in particular, just the entire game in general.

Or Castlevania. At least it had good music for me to hum.

Oh, and why is SMB3 so awesome?

In the US, Nintendo entered Extreme Hype Mode. Heck they even had a movie whose climax was SMB3. The ushers gave out free Nintendo Power subscriptions afterwards! Halo3's got NOTHING on SMB3's hype machine.

Having passed both the dam level of TMNT and level 3 of Battletoads, I must say that the dam level is a little harder.  I've got the racing in B-Toads down.  I can hit the warp every time.  In TMNT, I can pass the dam, but I usually have 3 of my turtles with 1% of their health.

It's not my favourite Mario but I don't mind it. I played it a couple of times and it gets frustrating at some points but it isn't too bad. I just iono I don't like the concept I guess. I hate those ghost ships, I find them annoying but that's just me.

TMNT is the hardest game I played and after say, some time I tried over and over and over again, I've told to myself "%&@# this game"!

ALttP is imo, only a bit confusing by times, like the dongeon in the mountains in the dark world. Gosh I hated that one.

Anyways, back to Mario my favourite in 2D had to be Super Mario World.

The seaweed is a pain in the ass.  But level 3 of Battletoads is loads of fun!  I usually try to pass it without warping -- the last segment where you go even faster (and the music speeds up for more adrenaline) is pure win, especially when they stop telling you where the next barrier is.  I often get tripped up at the surfing level immediately after, but I've passed that before, and the snakes after that are a lot of fun and not too difficult.

I'll second Castlevania, that game is already challenging on level 3, and it really gets hard around the Grim Reaper.

LttP is easy.  I've beaten this game without dying, in one sitting.  Multiple times.  Well not multiple times in one sitting, you know what I mean.  It's so easy, I invented a challenge for myself: Complete the game with zero unnecessary items -- no pieces of heart (or the first heart container), no bottles, no blue or red mail, no upgraded master sword or shield, no boomerang, nothing that you don't absolutely require to beat the game.  I eventually made it to Ganon's Tower, but haven't managed to beat it yet.

The only really tough part in Zelda: Link to the Past is the first Dark World dungeon, where the boss does 2-3 hearts of damage and you only have 9 hearts (if you've hunted for them!)

After that, squish dungeon 4, get the 3rd sword and pwn.

I just beat SMB3 last night, did most of it in one sitting (I was at the beginning of world 2m the sand land or something). I haven't played it since I was a kid, and I never actually beat it then. I remembered very little of the game, so it was almost like my first time through. Difficult? Yes, but definately not stupid hard, and very very far from being one of the hardest games ever. I still think the first SMB is harder just because extra lives are alot harder to come by (barring a certain 99 life trick). When I got to world 8 in SMB3 I had like 35 lives (I beat it with 12 mind you, there were a few levels that were pretty crazy. That first tank level coming to mind). But up until world 8 I never died more than a couple of times on a level, and alot of levels I didn't die at all on. Definately an awesome Mario game, and spectacular for it's time. But Super Mario World is still my favorite 2d mario.


As for challenging games, BattleToads on Game boy drove me mad. Never beat that game, I could rarely get past I think it was level 5 "Brain Damage" where a brain just chases you through a series of tunnels for what feels like forever. You just run, run, run, jump and the slightest error, it doesn't actually even have to be an error, it could just be less than absolute perfection and that brain crushes you. Man I hated that stage. And if by some chance I survived it I had few if any lives left to continue the fight. Dear god that game was evil.

Of course arcade games were far more difficult but that's because there was no victory possible. It would just get harder until you were dead.