Damn your blood that's blasphemy! Ninja Gaiden Black and Gaiden II are like my favorite games ever.
I admit they can be hellishly frustrating though. But then that is how Ninja Gaiden games are suppose to be isn't it?
It's been a few years, but I remember enjoying Ninja Gaiden II a bit less than the first one too. I beat it (can't remember if I was on Path of the Warrior or Mentor), but I was kind of relieved when it was over. The worst thing about it was the camera angles: The game zoomed in a lot so you could see how awesome you were, except that meant you couldn't see the body parts that some werewolf behind the camera was about to throw at you. You'd think you're doing really well, and then all of a sudden...BAM! You get rocked in the face with a hefty torso that would have broken the speed limit on the Autobahn. It does a ridiculous amount of damage and knocks you off guard, and you immediately get torn to shreds afterward.
If I want to die before I ever see it coming, I'll play a game that mimics real life war. When I play a ninja game, I want to play a total badass capable of defeating anything without a scratch...as long as I don't make a totally avoidable mistake, of course.
Ninja Gaiden II didn't make me feel that badly though. At least it wasn't Barbie: That game frustrated me to no end when I was a kid, because it made me feel like a total moron getting trounced by a little girl's game.
Anyway, the least satisfying games I've ever played were dissatisfying mostly because they didn't live up to my expectations:
For instance, I've held for years that the worst purchase I ever made was Quest 64. I can't remember much of it, only that I beat it in 12 hours or so, but it was so generic that it felt long. I also received an early NES-caliber ending for my trouble. It probably wasn't actually bad enough to deserve my everlasting judgment, but I was ravenous for N64 RPG's by the time it came out, and it just couldn't deliver...disappointing.
The runner-up would be the Halo Anniversary Edition: The original Halo multiplayer has been a minor religion in my extended family for years, and we were all so pumped to finally play it on Xbox Live after years of it being the most fun - and only online-incompatible - Halo game. (It was also the only Halo with a single human gun that I could fairly call futuristic: The "God" pistol. That's how video game guns are supposed to be in future settings with FTL travel...you know, more proficient than they are today, such that assault rifles don't take thirty shots to kill someone.) Anyway, all our dreams were cruelly shattered when it turned out the Halo Anniversary Edition would only include revamped single player (better graphics, narrower field of view, and strangely breaking some of the facial animation in cutscenes) and Halo: Reach multiplayer with cheap imitations of a few Halo maps. "Least satisfying" indeed, in the sense that they delivered everything but what we wanted.
The most frustrating games I've ever played - in and of themselves - are probably all older games with poor play control. I've repressed many of my memories here, but the Castlevania series comes to mind: It's one of the most beloved and classic series in all of gaming, but the controls were always so restrictive (especially around stairs) that I never could got very far before gently putting down my controller before I snapped and murdered it. Medal Gear Solid 2: Sons of Liberty would be a more modern game I can't play for the same reason. I don't know why they're so difficult for me to get the hang of though...so many gamers love both and have no issues.
OH, WAIT: Speaking of issues, the most frustrating game of all for me is Portal, because it's such a fantastically good game...and I can't play it without feeling horrendously nauseous. I'll start to feel sick if I even WATCH it for more than a few minutes, and the feeling won't go away for a while either. Any game based on Valve's Source engine (except Counterstrike: Source IIRC) seems to do this to me...or at least, Half-Life 2 did as well. I only got an hour or two into that before calling it quits forever. It probably has to do with the narrow field of view. I can't change it in Portal (Xbox), and Half-Life 2 kept fighting me and reverting whenever I tried to change it back in the old days (wrong command series probably, but I just stopped caring before figuring it out). Regardless, I hate that freaking brown note of a game engine, and I used to play twitch shooters like Unreal/Unreal Tournament for thousands of hours (not in one sitting) without issue. There's another recent game that made me a little queasy too, and it surprisingly wasn't a Source engine game, but I can't remember what game it was. All I remember was it only happened once, and it wasn't half as bad.
I never played E.T. though.