The 404 Challenge was performed by Stampylongnose in 2012. This challenge is no longer available in both PC and Xbox, however Stampy had a chance to play it before he updated the game, since the next update removed the challenge.
As you enter into the world, there's a big gravel pit in-front of you, but don't go there yet. You must gather up enough materials during the daytime. As the sun goes down, be sure that you are prepared for the next one. As it goes entirely nightime, break one gravel and it will fall the rest down for sure. Enter through the caves and stay there for the rest of your experience in the challenge. If you die, you lost the challenge (just like Hardcore mode.)