Battletoads was just brutal - even the best gamers had trouble beating that.
MGS1 on extreme was pretty hard when you got up to the Hind fight atop the Comm tower.
Also Dragon Age on hardest difficulty is pretty insane.
I don't know if it was because I just sucked at it, but no amount of efforts got me far in The Temple of Elemental Evil. Even random encounters would be party killers.
While not 'hard', Chaos Gate caused me lots of frustrations. You have no idea how many times I reloaded that game because I lost one of my best marines to a cheap ass Cultist spam. In a game where you need ridiculously high level troops to beat the last level because of the sheer number of elite enemies. And in the level before the last you need to kill a freaking Greater Daemon who WILL chew through half your army no matter what you do.
Oh, and old Rainbow Six games (Rogue Spear, Raven Shield) on higher settings. Peek your head around a corner, guard spins around and blows it off. Less 'hard design' more 'cheating AI has eyes in the back of their heads and 100% accuracy'.
Rogue Squadron on the N64. Very hard game. Even the beginner missions are tricky enough. The bombing missions though just take it to a new level - slow, poorly armed ship, hitting pin-point targets while interceptors chew off your ass. Great.
Lineage 2 Official .. 1x rates and omg long long long long long grinds.
Loved to play it though, been 4x duelist (loads of olympiads) and clanleader/castle owner <3
Games i play these days are much more easy
Left for dead 2 HARDCORE mode := or whatever you call that hardest thing :P
The Game you all just lost.
Counter Strike Source (rage!!!!1111!!!!11!!1)
much flame Inc. But...MW2....It was just the first shooter game I played on a console and I started out veteran. Ofc I'm now great at it but I sucked for so long lol.
Guild Wars: Eye of the North with NPC is pretty tough.
Diablo II, the last chapters in Hell difficulty!
Chaos legion.... almost nobody knows it for pc.
Theres that damn endboss wich JUST DOESNT FUCKING KNOW WHEN IT HAS TO DIE.... he dies... oh stage 2..... again again again.... OH FUCKING STAGE 5.
It took me about 150 trys until it was dead without the last ultimate spawnable creature
Falcon 3.0 and Falcon 4.0, they gave you a 400 page manual
I stuggled with Battletoads, but i was like 8 wen i was playing it.
God of War 3 on the last difficulty is pretty frustrating at times, although not impossible.