I'll go first. Man attempts and succeeds a no hit, level 1, charmless (hard mode) Demon Bell (extra hard mode) at the final Sekiro boss on New Game +7. 

I've never seen such dedication. Over an hour long, no mistakes. For anyone who doesn't know this fight, imagine the hardest boss you've faced in a game and it'd be equal or more so, on a normal encounter your first time. Each NG+ increases boss difficulty and so does being charmless and having rung the Demon Bell in game but to top it off he doesn't upgrade his characters attack power, essentially being Level 1 and does it all with the stipulation of not being hit once. Absolutely amazing. 

Halo 2’s Deathless LASO (minus Envy skull) run that was finally accomplished a couple of years ago. One of the most thought of impossible feats in all of gaming.

There had been feats accomplished before but, it included the Envy skull which gave Master Chief active camo rather than a flashlight which naturally gave players an advantage. So Moist Critikal/Penguin0 put out a bounty on whoever could accomplish the feat first.

For point of reference, Halo 2’s Legendary difficulty mode is notorious for being completely unfair. Everything one hit kills you and you can get to points where you’re insta-killed as soon as you spawn and there’s no getting around it.

And just for added difficulty, you have to have all the other Skulls (modifiers) enabled. Including the Anger skull (enemies fire weapons faster and more frequently) and the Assassins skull (all enemies are permanently cloaked, so you can barely see them) 

And there’s like 15 skulls in Halo 2. So yeah, it was thought of to be pretty impossible. Along with, NOT dying a single time through the entire run. Thousands of people went on Halo 2 accepting Moist’s challenge and it was a special moment for the Halo and gaming community when the feat was finally pulled off.

This guy who 1CC Ikaruga with 2-player mode. One hand for each player. I cannot express how impossible this is. The game alone is one of the most difficult games to master in the genre. Which is one of if not the most difficult genre that exists.

The 5-4 skip in Yoshi's Island is still one of the most impressives feats I ever saw in a classic game.

In this level, you need to get a ride from a platform monster in order to cross a large room. But 2stop, a Yoshi's Island speedrunner, found a way to skip the whole ride by floating through the bottom of the room, while still getting all itens.

If I remember well, this was found back in 2013. It starts at 1:59.

Holy hell

Idk what I'm watching but it looks impressive all the same. 

It has to be some SMB speedrun stuff if we're being coldly analytical about it, there's just so many people putting in so many hours and the result can't be anything short of perfection.

That being said, there's some really cool stuff out there.

This is the ultimate ishin 10x harder also not ruined by the lame character you had in your video. This is the most impressive feat ever and nothing comes close.

The blind guy who beat OOT. Too bad he didn't get to see it himself though...