So we all know about that evil little Japanese Mario-like game by now, yes? Well guess what? There's a game that's even more of a bitch. And that game's name is... I Wanna Be The Guy.
It's epic most definitely, but also TOTALLY unfair in how it kills you. Plus it has actual bosses that were a bitch and a half in their own time. I've only made it as far as the first boss (MIKE. FUCKING. TYSON.) and that was with the help of a guide almost the whole way through.
IWBTG is a twisted cruel game, and you'll hate it so much, yet keep coming back for more. It tracks your deaths, but it's so much easier to die randomly than it is in Pyoron. Hell, I only died in that about 100 times...but I'm over 100 deaths in IWBTG, and nowhere near the end. The screenshots on the site? Have never seen them in game.
So, yeah. Download the game, tear your hair out, and curse my name for the years to come :D.
PS - I suggest playing on MEDIUM (as there's no easy difficulty) difficulty. The added save points are really helpful.
PPS - This came AFTER Pyoron. To quote the FAQ...
Q: Why is this game so fucking hard?
A: A whim, really. I played a 2chan flash game that was stupid hard and thought "Hm, I can do better". I needed a practice project. It just happened to grow into a big game.