Kirby's Adventure is pussy, I agree with what Torian said

All MegaMans are freaking hard, even 9
Yes, Megaman is an absurd!
Ghost and goblins for me if you made to the last boss without the right weapon , shield or whatever was it you needed to make all again ==.
Adventure Island games (except 4th) are really hard ones to beat
I have three Adventure Islands here. I don't like so much...
The NES is hard.
Not really, I think the hardest game was ethier SMB2 US or SMB3.
Nah SMB1/2/3 are fingers-in-the-nose games. Bionic Commando, Solomon's Key, Ghosts'n Goblins... are much more difficult to complete
Silver Surfer will own you. Or just about half of the other NES games the AVGN has reviewed.
No wait...... The Adventure Of Link is the hardest.
Maybe it's just me but when I played punchout, once you get to the last few fights it became very difficult.