While Activision reinvigorates the Guitar Hero license with World Tour, it can't very well leave potential Nintendo DS money on the table. So following the success of On Tour (the handheld rocking game) comes a sequel/expansion. On Tour: Decades is basically a new song list, with the songs arranged in sets for particular decades, each played in a decade-themed venue. The idea is that you start with contemporary songs and unlock sets backward through time, going all the way back to the '70s. Anyone for a visit to the discotheque?