Someone or something that is universally recognised as being the best at something, especially gaming. Often referred to as being 1337 or leet. Skills are unmatched by any entity, not even a Jedi Master! Others are often surprised at the difficulty of taking on such a warrior.
"Hey, check out Alex on Counterstrike, he is Atmosferik tonight!"
"Look at Atmosferik go... I wish I was Atmosferik."