Activision has forgone an official agency review in handing over its Guitar Hero account to TBWA/Chiat/Day, reports Ad Age. Activision chief creative officer Brad Jakeman said the decision was principally based on the outstanding work TBWA did for the Call of Duty sequel Modern Warfare 2. The game’s campaign has become one of the biggest entertainment launches of all time. Guitar Hero creative was being handled by Crispin Porter & Bogusky, the agency responsible for the string of star-studded Risky Business spoof spots for games from the series including Guitar Hero 5 and Band Hero. Activision’s media buyer Mediaedge:cia is unaffected by the transition. Ad Age says Activision spent $84 million on advertising in the US in 2009, $5 million more than the year prior. The publisher’s account is now expected to be split between TBWA handling Call of Duty and Guitar Hero titles while a second agency, Droga 5, handles the rest. Read more at Ad Age.