The hardest game I think:
N64: Legend of Zelda: Ocarina of Time
Gamecube: one of the Final Fantasy
PS2: Star Wars: Battlefront 2- only really adventure most are sport
Xbox 360: Turok

I've only played games since the PS1 was released, so, I'll go from there.

PS1:
Abe's Exodus
Thunderhawk Firestorm 2

PS2:
Killzone on hardest difficulty
Champions of Norrath on Hardest Difficulty.

Gamecube:
Metroid Prime (I bought it for a fiver, tried to kill the plant boss)

Xbox:
Halo 1 and Halo 2 on Legendary

Xbox 360:
Halo 3: Campaign scoring on Heroic or harder with 5 or more skulls active
Call of Duty 4: Modern Warfare. Veteran is a hellish grind. I'm on Shock and Awe.
Kingdom Under Fire: Circle of Doom. That game is pointless, it's broken. I've completed it once, got 300 gamerscore and tried to go through it again. I got bored and some stupid blue lizards kept killing me.
Guitar Hero 3, Expert Career. It's hell.

PC:
Sins of a Solar Empire. It gets tedious after about 24 hours played on a single game.
OpenTTD. It's hard to pull off a good business model.
Sim City 4. How can you profit on it? HOW?!

Metroid was annoying, the newer ones are MUCH easier. The level "Cortana" in Halo 3 on legendary is almost impossible, Ghost Recon AW1 (in terms of achievements) is difficult (you have to reach number 1 WORLDWIDE on certain playlists), Gears 1 and 2 on Insane... I was about to rip the hair out of my arms because i couldn't kill the Leviathan, even with my friend. And lastly, CoD4/5 on Veteran. Talk about Impossible.

Has anyone ever played Mario Tennis for the GBA? I just found it buried under piles of junk in my room, but this game is tough. For each level up you get to choose one of four stat groups to put the experience into, but most of the time when you don't put the level into one stat, one or two of the other options will degrade, making you have either balance your stats evenly, or just never put anything into certain ones to begin with.

I didn't even know that there was a tennis game for the GBA. ._.

mario tennis for the gba...
really man look around this topic
that game is nothing
or are sports just your weak point

one hard game i know but cant remember the name

you switch between weapons[swords ect]
level 1:a graveyard with fire breathing stuff, dungeons that trap[auto kill you when you near] and skeletons with strechy arms
level 2:a sea with giant nearly unavoidable tidal waves that take up the entire screen[dont know how to dodge]and drowning tide constantly

no bosses

go beat super mario brothers:lost levels[the real super mario brothers 2 i think] without getting hurt/touched no falling once at all twice in a row and then try this game

you'll be lVERY VERY VERYLucky to get to level 2 then 1/1500 you'll die IMEDIATLY

after 3 years of trying you probably never made level 3

I have beaten SMB: The Lost Levels on Super Mario All Stars, and without warping, thus gaining me access to the hidden World 9. I've also beaten the original version for the NES (SMB2 Japan) multiple times through on Virtual Console.

It's not that hard. Most of it is memorizing jumps, enemies, and traps.

the first time you ever play the game i mean

and besides you've only beaten it reread

I'm surprised i got through the level where you have to find al assad through the villiage. I'm on the "All Ghillied up" part where you snipe the guy in the arm. The ferris wheel part reallly ticks me off. i shouted many f-bombs while my dad and siblings were in the house >___<

Ninja gaiden II, hardest game ever.

EDIT: Nevermind, Click here.

Just got bomberman max champion blue version for GBC. It is very very difficult.
having to start levels over after getting hit ONCE really stinks.

megaman 2 and echo the motha f:censored:g dolphin

The hardest game I have ever played has to be I wanna be the guy. That game is out to get you at every opportunity.

Pikmin 1. It's beatable, but getting the good ending, is IMPOSSIBLE!

Arcadia mission in Haloz: Wars.
GOD DANGIT BANSHEE YOU ARE NOT A SKILLED KAMIKAZE

I found Guitar Hero World Tour on expert to be reasonably hard, however, the hardest game for me has got to be Tom Clancy's Rainbow Six Vegas on Realistic. Two shots and you die. If enemies have machine guns, its almost impossible. To complete all missions it took me about 5 months.... Waste...

My hardest would be the ninja gaiden series or the devil may cry series
i've been playing a little bit of devil may cry 4 on ps3 but its so hard

After spending three straight and excrutiating hours playing the Portal challengs (portals, steps, time), I can honestly say that the "Aperture Science" achievment is the hardest Xbox360 achievement I've earned so far. "Neighborhood Watch" was a pain up the butt too.

Also, I have not beaten Castlevania IV to this day. I'm permanently stuck at the part where you have to climb falling staircases as a giant clock-gear-esque thingy rolls up from the bottom of the screen (one touch = instant death). If I manage to get past that part, I always die at the floating platforms part where they put spikes at all the wrong places to kill you.

Battletoads and IWBTG. If you've played these and not ended up swearing loudly at the screen, you're not human.

The hardest game i can remember is Rachet and clank 1. I remember drowning every minute

For me it would be Farcry on the hardest difficulty. It's just wtf.
From my childhood, Super Monkey Ball 2.

Prinny: can I really be the hero for PSP. I was stupid my first run through and saved the harder levels for later in the game. The game gets progressively harder as you go through the game and time passes since netherworld citizens get stronger at night, and since you can complete levels in any order it's in your best interest to take on the hardest levels first instead of crying tears of blood later. There's also a Hell's finest mode. One hit and you're dead.