Questions about difficult video games.

1. What is the hardest video game you've ever played and why was it difficult?

2. What is the most difficult video game you've managed to beat? (Legitimately/Without cheating)

3. Who is the most difficult boss character to defeat in a video game?

Battletoads (US NES), Raiden 1 (PS), RSG, numerous bullet hells, and Gun Frontier. Battletoads is sheer memorisation and after lv 4 garbage lv design, to the point that it's absolutely no fun which in itself raises the difficulty--I find TMNT much the better/funner game despite respawning glitches and inferior controls. Raiden 1 is just too much firepower against me, and I suck at shmups. RSG is a puzzle plus shmup, and I suck at both; plus it's Treasure = insanely dull and aesthetically repellent. Bullet hells are puzzle games plus shmups, and I suck at both; they also exploit my small degree of passive colour blindness (the member Ecco seems to have a similar problem). Gun Frontier features one of the slowest ships ever, even slower than Raiden's, with checkpoints that just make me want to chew off my foot...and I still suck at shmups.

I've never beaten a difficult game. If I can beat it it's easy. This holds for PhSII, SFIITurbo (Arcades, 1CC), Battle Garegga, Kid Chameleon, Bayou Billy, Bart vs the Space Mutants NES (which has perfect control by the way), the great majority of SNK fighters on Saturn (max dfc), Rolling Thunder 2 and 3 (1 is too hard the second time through).

The hardest boss character = Neifirst.

1. NES Castlevania. Frankie and Igor are near impossible to get past.

2. Ecco - The Tides of Time

3. Frankie and Igor, NES Castlevania

Dragon Warrior 2 is evil(Everything about the game is against you, you can't over lv, the enemy AI basically says focus fire the weakest char, the dungeons are complex mazes designed to make you get lost, thus running into more battles, and some of the dungeons have insane traps). Aside from that the Wizardry games are hard as hell as well(two words "Perma Death", on top of that the game constantly auto saves), the key to that game is caution, however the slightest mistake could ruin all your hard work(literally the slightest mistake or bad luck).

Dragon Warrior 2 by far. However I've beat other insanely hard games as well, Contra(no life code, and I only died once in the entire game), Dr Jekll & Mr Hyde(It's such a POS game, I couldn't let it get the best of me), Faria, Link, Hoshigami, Gradius, Silver Surfer, exc.

This is a hard one, I played so many games with hard bosses, I can't recall which ones were the hardest.

1. IDK...I have a somewhat moderate threshold for difficulty. After a certain extent, I'll just give up.

2. Viewtiful Joe on adult mode.

3. Are you looking for a subjective or objective response?

1. Probably Spike Out Battle Street on Xbox in single player. That game requires you to master the gameplay and keep as many opponents on the ground as possible by the fourth level. I love group fighting mechanics and have never finished it.

2. Shadow Dancer on Genesis and the Arcade

3. In my opinion Zoddo the Immortal in Sword of the Berzerk on Dreamcast is the hardest boss ever made that can be defeated with skill (rather than luck or trial and error/memorization).

1. It's hard for me to answer this question, partly because it's hard to separate it from #2 (can I really speak to a game's difficulty if I haven't completed it?) and partly because there are a bunch of competing definitions of "difficult", e.g. the 20-minute psychological torture test of attempting a perfect score in Pitfall vs. the 8-minute gauntlet of Marble Madness vs. the non-time-limited agony of Sol-Feace on Mania vs. blah blah blah.

But, um, probably Dragon's Lair for NES, because it's just unremitting and crushing and joyless and...how did the designers look at themselves in the mirror, really?

2. I think Adventure Island for NES is probably the one. Getting through the last few levels without a weapon, and without running out of energy, required essentially perfect platforming at high speed. Otherwise, some of the games I mentioned at the end of the previous paragraph.

Clearing Level 20 on Dr. Hello (a Dr. Mario clone) also demanded near-perfection, but is it really the same when you can instantly retry?

3. It's been too long since my NES days to answer this properly. Maybe something from Ninja Gaiden (I or II). Or Batman? Sunsoft really seemed to like razor-sharp bosses.

I don't have an answer for #1. Hardest ever is too subjective. Probably some bullet hell shmup.

The most memorable challenge that I beat (right now off the top of my head, and maybe influenced by tz101's answer...) is Ecco the Dolphin CD.
Back in the 16-bit era, I beat almost every game on the same day as I purchased it, or if it was a long game (RPG etc) within a couple days.
Ecco the Dolphin has a lot of levels, so it took a good bit of time, and some of those levels definitely had me stuck for more than a couple tries, but I was making steady progress toward beating the game. Then there came "The Machine" level. With it's forced auto scrolling maze, instant deaths and level restarts became frequent. It was certainly frustrating, but I finally had it memorized so it was no problem. But then there was that final alien boss. God damn, you die there then it makes you redo the whole "Machine" level again. And I died a lot. It took weeks of returning to that game and I could never figure out the "trick" to avoid dieing on that last boss. I finally squeeked out a victory. Only once.

Batman CD driving sequences are damn hard later in the game also. Sega CD provided some pretty great challenging games, considering it's limited library.

Silpheed on Sega-CD is the one game that I never properly beat, despite the fact that I think I could say I had the rest of the game "mastered."

It just dawned on me; I do have a definitive answer for the question of "hardest game."

Hands down the most challenging game that I've played, and that just wasn't a broken poorly designed piece of crap,
is Finger Flashing on the Playstation.

That Twin Dreams write-up I linked gives a very good overview of Finger Flashing. I read that page before purchasing the game, yet I was very unprepared for what I experienced in the game.
Such a simple concept is made confoundingly complex and challenging ...yet still entirely simple.
My brain literally gets overloaded trying to play this game.

It is a paper/scissors/rocks shooting game of sorts. The scroll rate of the playfield is controlled with the shoulder buttons; the faster the scroll the higher the score multiplier.
Then there is the chaining of enemies for another score multiplier. So to score effectively the player has to speed the scroll rate up while also taking out large groups of enemies with single shots. It gets very tricky, very quickly

1. What is the hardest video game you've ever played and why was it difficult?
Contra: Hard Corps. 'Not enough hit points to get ahead properly.

2. What is the most difficult video game you've managed to beat? (Legitimately/Without cheating)
I used to think it was Truxton, but then I noticed it was easier to beat it in "Normal" than in "Easy" mode; due to a slight change in power-ups. Mickey Mania (Sega CD) wasn't exactly a walk in the park either, but it was not much more difficult than, say, the final boss in Tiny Toon Adventures: Buster's Hidden Treasure. In other words, most platformers will get easier as one memorizes the levels (heck, probably even Contra). For now, I'll give it to Jackal on the NES.

3. Who is the most difficult boss character to defeat in a video game?
The toughest boss I've ever defeated was Dracula in Castlevania: Circle of the Moon on the GBA.

1. Castlevania (NES) mostly due to Simon Belmont getting knocked back after he gets hit, although those little hunchback creatures were very annoying as well.

2. Contra on the NES.

3. Akuma from Super Street Fighter II: Turbo.

Great Guriannos on the Spectrum was pretty tough, Dave Perry ran out of memory and time to finish the game so he gave one of the bosses infinite health ;)

Castlevania II on the NES was very difficult, bad localization was partly to blame as a number of location names and clues were sloppily translated. I somehow managed to beat it back in the day without cheating. Don't ask me how though.