What is the HARDEST game you have ever played?! GA INSIDE!

Probably Fly'n.
It might have been due to only having a crappy laptop and no controller though. Maybe I should try playing it on my PC.

Any Souls game can be really hard if you want it to be, some ppl play them with no equipment or level 1 just for the challenge. The Binding of Isaac Eternal Edition was hard to 100% (more than Rebirth+Afterbirth for me). I haven't finished Super Meat Boy so yeah it's hard.

Jamestown should get a mention here.

probably some Nintendo game i forget about after ragequitting ;p

Ghost'n'Goblins
SuperMeatBoy
HardestGameEver 1,2 for android
SuperHexagon

Red Alert 2, that final boss battle, just bullshitly difficult XD in its normal form it already kickass your ass but when you beat its first form out pops the enemy and has a new health bar, but now he insta-kills you if he hits you , it was to hectic to beat without setting the game to easy XD

Jak 2. I was surprised how tough it was

Try Catmario! guaranteed u will have a blast

Good hard or dumb and unreasonable hard?
Fenix Rage started quickly moving toward the latter about halfway through. The environment and enemies did not reset positions when you died and respawned, preventing trial and error movement memorization, and it even became necessary to manipulate this fact in order to complete a level. (Devs said it was intentional, but it screams bad game design to me. No other well-made platformer does this, to my knowledge.) I gave up on the game soon after encountering the enemies that chased you around the entire screen, flying through walls and almost never stopping.

Devil May Cry 3, super hard, had to grind A LOT everytime I reached a boss cause I wasn't powerful enough. I didn't even finish it

For me Rainbow Six Vegas 2 is pretty hard. Although short.

Blackhole. For those who dont know its a 2D hardcore puzzle game, first game when i give up. The story is not so much interesting so i recommend this only if you want get all the points and stuff. In every level there are these points (selfburns) and you need like 2 of them to exit the level, they are easy to get but the rest arent. So if you are tryhard hardcore player that really wants to get everything then and only then buy the game.

Flappy Bird

Shinobi on PS2. That garage level, man. After breaking a controller, damaging my TV and days of raging, I finally cleared it. And then I turned off my PS2 without saving.

Legit was never able to play that game again.

VVVVVV Theres a secret collectible (trinket) that requires you to go through tunnels of spikes without checkpoints Video

With cheats: Battletoads probably
without cheats: any Mega Man game
so difficult I never beaten it: SpaceChem

Hotline Miami 2, the Hard Mode difficulty... good luck getting S ranks in every stage.

How hard?
Enemies have a faster reaction time
No sticky crosshair (you mark the enemy you want to kill and you keep aiming at him till you kill him)
Enemies can see farther than you do forcing you to hold down the "Shift" key to check the area for enemies
Guns ammunition is reduced every time you throw it (i. e. double-barreled shotgun - current ammo: 2, when you pick it up from an enemy: 1)
More special enemies (fat guys - can only be killed by guns, ninjas - guns are useless against them and dogs)
And the overhead view is turned upside down, forcing you to relearn the levels.

Battletoads for NES :p

Mine Sweeper.

And yeah, Super Meat Boy... that shit is rage quit no. 1

BATTLETOADS Nes :S frustrating

Super Meat Boy and the final Boss in Banner Saga on hard difficulty

Not counting Dark Souls.
FTL, I can get to the end but the boss just slaughters me

VVVVVV & Super Meat Boy.. I suck at platformers... ;____;

View attached image.

Super Meat Boy, like everyone else has mentioned. Crypt of the NecroDancer is really hard for me too. Maybe I just suck at it D:

I don't know really. After beating a game I forget if it was hard or not. I just remember it as a joyful ride and one game less in my backlog, but thinking about it... There were a lot that had me play levels over and over and over and over again. Especially some Devolver Digital games. Tital Souls for example where you have to land one precise shot, but to get there you have to memorize the boss' movement etc.
Hotline Miami and Not a Hero as well. In the trailers they looked like fun run 'n' shoot type of games, but no, there's actually skill required.
Heavy Bullets as well... I'm a Devolver Digital fanboy, sorry :D
Uhm, but time-wise probably The Binding of Isaac. Took me 30+ hours to kill Mom and she's not even the final boss. ;_;