Vulture.com just put out a list of the Top 100 Hardest Levels, based on the following rules:

• No endless levels
  
• Side missions in Open World games also count
  
• Difficulty also scales to intended audiences

While I'm happy to see Sonic nab a spot at 84 with Hydrocity(seriously though? Not Eggmanland? Or Labyrinth Zone?!), and the obvious culprits are of course making their appearance(The Library, Bioshock, God of War, Mile High Club, Lion King, etc.)...but one made a spot that I honestly didn't expect, although I fully agree:

Number 39 was King's Fall, the original D1 raid. It's funny, I consider King's Fall to be the best activity ever in terms of lore and encounter design. However, that was marred brutally by strict timing conditions, demanding network performance, and unpredictable AI behavior. Not only did all six Guardians have to be perfect—all six of their internet connections had to be perfect, too. So many wipes attributed to brands running out or platforms appearing out of order, even though the less-than-hardwired player swears they performed their task on time...

And Oryx's chest, man...always so inconsistent! Sometimes he'd charge his whole attack and succeed, despite six people firing Touch of Malice at his Dragonheart, and sometimes he'd falter instantly. And don't even get me started on the 16 bombs challenge, dear GOD. I can't tell you how many hours I spent on the hull of that Dreadnaught sitting and waiting for the raid leader to scramble and make an LFG post because of rage quitters. King's Fall is my 2nd favorite raid in the whole series...and I never want to play it again.

How could they leave out mission 5 on Metal Slug 3… it's longer than most arcade games were in their entirety. Few can beat it without continuing.