Possible Clues:

• Video game series with a Warriors of Rock edition
• Video game where you wield an ax and slay?
• Video game series with strumming
• Popular musical game beginning in 2005
• Video game that comes in a World Tour version
• Hit video game series featuring 'hammer-ons'
• Hit video game series since 2005
• Hit video game in which it's really easy to be one button off
• Hit video game series launched in 2005