pssssh, I recently beat Contra and died once, the game is like 10 seconds long.
I used to think Ninja Gaiden was tough, but that was when I was younger, I've had no trouble beating it (and the only part that's actually kinda hard is the part right before the end boss, and then the end boss is cake).
Ikaruga.... on Hard mode... that that's practically fucking impossible. You deal with situations that you've been through like 20 times and you STILL don't know how to survive some parts...
Gradius 3 IS FUCKING IMPOSSIBLE on arcade, I've only ever beaten it with save state.
I was going to put 1943 as a tough game, but I just fuckin beat that one recently too! lol
TMNT, never beat it, but never played it past the age of maybe 8.
I need to try these megamans "zero" games... X6 was somewhat challenging, and I'm not having much trouble with zx on the DS... just don't play it much really. plus it's annoying to find that right button for dash.... just because you can't holy y, press a and then b, and having dash as x is just weird..., so i use top r. and there's too much god damn storyline and searching for missions and shit, buggin the hell out of me.
and the game I don't know if I ever past the first few parts of, which I think is definitely the hardest game ever (besides something like populous or some fucked up weirdo nobody puzzle game where there's like 1 billion levels)...
which I haven't played past the age of like 6-7 either... but I remember it was just fuckin impossible