Activision Blizzard has revealed that Modern Warfare 2 has passed the $1 billion USD mark in worldwide retail sales since launch.According to estimates, Modern Warfare 2 – which launched back in November – has not only sold more than $1 billion USD at retail, but in its first five days it sold $550 million USD worldwide.$550 million USD in five days is nothing to sniff at. Apparently, that beats the five-day box office grosses for Avatar, Harry Potter and the Half Blood Prince, and The Dark Knight.Unsurprisingly, Activision is rather proud of this achievement. “Call of Duty: Modern Warfare 2 has exceeded our expectations and shattered theatrical box office and video game records,” said Activision Blizzard CEO Bobby Kotick. “There are only a handful of entertainment properties that have ever reached the $1 billion [USD] mark, which illustrates the power of the Call of Duty franchise and mass appeal of this game.”Thankfully, I won’t be spending the evening crying blood in despair of people buying a terrible game, because Modern Warfare 2 is really rather special. It scooped a few of our, and we .