Hades Challenges started as Peachy Weekly Challenges while the game was still in Early Access. They were created by HeartfulPeach on Official Supergiant Games Discord as a way to provide something fresh for players who played the game for some time. Tiank, Firespirit and Tatz helped with the challenges for some time.
After 1.0 launch the Challenges are continued in a bit different form (twice a month instead of once a week) by Nyaanyaa Mewmew and RidiculousHat.
The Challenges are open for everyone, who'd like to try themselves, however, keep in mind, that they often need some stuff already unlocked and are meant to be hard.
So don't be shy, try it, either for your own satisfaction or to share your achievement with others! Check out this link for more info and available challenges!
And remember - have fun!