I don't play video games but this level of sales sounds pretty phenomenal especially since the article states the game has not yet gone on sale in Japan and Brazil. In addition there is the matter of theme for which "Grand Theft Auto" is well known (yes, well, I know that much):
Game revolves around a trio of criminals as they pull off heists in a fictional version of Los Angeles, known as Los Santos. Appeal of the franchise over the years has been the ability to veer off and explore the city, stealing cars and causing mayhem.
Kinda disquieting given what we know about Aaron Alexis and his favorite pastime.
http://variety.com/2013/digital/news/grand-theft-auto-v-earns-800-million-in-a-day-more-than-worldwide-haul-of-man-of-steel-1200616706/
