While we were quietly looking forward to Guitar Hero II, secretly reminiscing how we used to strum tennis racquets to Dire Straits' 'Sultans Of Swing', a few gaming sites are speculating that Activision has actually dipped their speedy Van Halen-like fingers into as many as four new Guitar Hero titles. Gulp.

The rumours, it seems, have been sparked by Joystiq, who cite an "anonymous source" as spilling the beans behind "potential" development plans. In fact, it's even gone as far as beefing up the talk with possible project names - Guitar Hero: World Tour, Guitar Hero: Encore, and the best of the bunch (simply because its name implies a bunch of classic Metallica), Guitar Hero: Axe Grinder.

Unsubstantiated rumours, of course, and ones which we've so far had no joy from official sources regarding their authenticity.

However, considering that Activision spanked considerable sums to land Guitar Hero developer RedOctane, and trade weekly MCV were reportedly told that six series games could release by mid-2007 back in March, it would take a big fool (a drummer?) to suggest that the Guitar Hero series will stop at Guitar Hero II.

Oh, and incidentally, Guitar Hero II looks likely to release later this year.