Can't say I'm talking from a lot of experience, but the turtles arcade game has got to be the best arcade game ever made!

GTA San Andreas, the flight mission after you get to the third section of the game.

There is a castle? Lol I can't even make it that far

First thing that pops into mind are those annoying Medusa heads from the Castlevania games. Hated coming across a room with those things flying around. Would always get knocked back at least once, usually at the top of a tower or similar structure, trying to navigate around those damn things.

Quillboar in World of Warcraft. Not because they were hard to fight, just hated the squealing noise they made.

Yeah that's fair. Perhaps I should have added a disclaimer : 'best, if you have infinity quarters' :)

and those NES turtle games (based on the arcade version) were tough as hell - almost as tough as the turtles game that got released on dos (which I think was ported from the NES - attached pic)

I remember that one on the NES, never played the PC version. At the time, we were mostly doing Flight Sims on PC F-117a and F-15 Strike Eagle II (I think II). I could never get passed that one. I think I made it passed that water part once out of sheer luck.

I also eventually got through Golden Axe on the Genesis/Mega Drive and I was so excited to try the Golden Axe arcade now that I knew my way around and the machine was replaced when we returned to the arcade. Was a very sad day.

I see your medusa heads and raise you these bastards :

oh gods. .. medusas without the snakes! AHHHHHHH!!

Enemies from Amnesia: The Dark Descent. Playing the demo was enough for me.

"Sees a humanoid figure in the dark. Nope. Nope! NOPE! Run away!"

:) the snakes were on the ground : http://www.youtube.com/watch?v=c-rZhUkAtlc
the most godawful thing about them was that scream...
Wow nice - I've actually met someone on the internet that played F117! I'd be even more impressed if you told me you played F19 as well! I played F117 to death back in the game, but not as was intended unfortunately. I always played with the setting that essentially turned the plane into a full on fighter with machine guns. I.e. I entered into dogfights with the F117 :P It was such a great game though. I remember this one mission required me to take out a power plant / factory. For some reason I ran out of bombs and mavericks so I decided to eject while on a collision course with the plant. It worked, and my F117 plunged right into the plant destroying it. I was a bit perplexed that I got I low rating for the mission since I thought that I was really heroic. In retrospect of course, I can only imagine the anger of my superiors at me for sacrificing an expensive top secret F117 only to take out a single target :P

I mentioned before I agree with the frustrating hit-or-miss platforming during the last stage of Valdis Story, but that was a "light nope" moment. I managed to finish and largely enjoy the game. Most games that had "nope" moments, for me, are games I gave up on due to those same moments.

I don't get scared by video games, so monsters and jump scares are far from being "nope" situations (not saying this in any macho way, it just happens that I got desensitized by watching way too many horror movies when I was a kid; horror in media doesn't scare me anymore).

My most recent memory of a huge NOPE was when I listened to the Shadow Gun sound effect in Shadow Man. Nope. I can't endure a whole game of that. I guess I got past the first area, got some sort of upgrade, but that gunshot sound was driving me nuts and I just called it quits.

Other "nope" moments usually happen when some mechanic is broken, or if I thought a game was real time but turns out to be turn-based. NOPE. No way in hell I'm playing those.

Fuck Lobstermen. I love the first X-Com, but TFTD was just insane. They may present you with several difficulty levels, but I think we all know there's only one level of difficulty for that game, and that is Motherfucker. NOPE.

The X-Com games are just too good a source for NOPE moments, though. Interceptor getting nearly one-shotted in encounter with large or very large UFO? NOPE. First encounters with Chrysallids? Cyberdiscs? Mutons? NOPE. NOPE. NOPE. Very large landed UFO in the early game manned by sectoids? Yeah, that looks like a big glass of NOPE right there.

As for other games, wandering into Shadow Beast lairs fairly early in any of the Gothic games and just seeing the dark silhouette of those things. NOPE.

Or one time in STALKER (SoC), seeing a pack of about 40 wild dogs all rushing straight for me. NOPE.

I did play F-19. Though a bit later we had F117 before F19. I remember playing it very mission based but I sucked at landing and would end up flying the plane. Then last bit get shot as much as possible eject near base. Complete mission and get purple heart. I think I was awarded the purple heart 47 times by the end of it. I never even considered hitting a target with the plane in a heroic attempt or the fury of the superiors. I always thought it completed the mission they are happy. Though I must confess I played F-15 more found it more fun just because it had more fighter intercept in it. I always disliked bombing runs because I would run maveicks mostly and the limited number you could carry. I also remember Chuck Yeagers Air Combat and beating my brother in a FW 190 and he was in a F-4 Phantom was very proud of that moment.

I remember that so well. On my way back I'd get hit by a missile or two disabling some of my systems. If the gear went out I knew I would have to eject, but the absolute worst was when the fuel lines were cut and you started leaking fuel. Then I'd hope and pray I can make it to friendly territory before I had to eject. Unfortunately I missed most great flight sims after that :P In fact, apart from demos, I only really got into two other flight sims. The one was a helicopter combat flight sim, (of approx the same era) which was surprisingly good, and the other was F-16 Fighting Falcon by Novalogic. The latter was an awesome title. They made two more with the same engine : F29 Fighting Fulcrum, and F22 Raptor.

Oh yes, and another thing I remember distinctly from F19 and F117 : The questions at startup where you had to identify aircraft from top-down diagrams. That is where I first starting learning aircraft types :)