This is world first people. After nearly 5 weeks since the game's release, a Diablo 3 player named Kripparian is the first to beat the game on Inferno Difficulty with a Hardcore character. What's Hardcore? It means that if you die once in the game, your character is gone forever. All your items, all your money, and all your time goes away with one single mistake... or even lag. It has been done and it is really no easy feat.
Diablo 3's Community Manager Bashiok has confirmed that this kill is indeed the first in the world.
With the help with his buddy Krippi, they took the hardest boss(Diablo) down and not even with the best gear in the game. It wasn't a perfect record though. Both players have lost level 60 characters in order to reach this goal, making this an even bigger accomplishment. Why? Because after losing their characters, they were forced to re-level and gear up their new characters all over again, which takes time. With a couple of deaths slowing them down, they still manage to do it in less than 5 weeks. Kripparian and Krippi have been live streaming their Diablo 3 gameplay since launch and I actually saw the kill live when it happened.
The world first was also done hours before Blizzard implemented the 1.0.3 patch that pretty much made the hardest difficulty easier for players. Another reason why this is such an amazing achievement. Don't go hating on Blizzard for making the game easy, since we now have a world first. These guys literally played almost everyday since release.