Guitar Hero III: Legends of Rock is a music video game developed by Neversoft published by Activision and RedOctane. It is the third full installment in the Guitar Hero series, and the fourth title overall. Guitar Hero III was first released for the PlayStation 3 and Xbox 360, with the PlayStation 2 version developed through Budcat Creations and the Wii version through Vicarious Visions. Aspyr Media assisted in porting the game to the PC, and Mac platforms in late 2007. Due to the acquisition of RedOctane by Activision, Harmonix Music Systems is no longer involved in developing titles in the Guitar Hero series; instead, they developed the competing Rock Band.

Guitar Hero III: Legends of Rock retains the same gameplay as the other games in the series. The player uses a special guitar-shaped controller to simulate the playing of rock music by playing in-time to scrolling notes on-screen. Guitar Hero III includes a new cooperative career mode and "Boss Battles" against both in-game characters and other players; the game is also the first in the series to allow for online play for the Xbox 360, PlayStation 3, and Wii versions. The game features over 70 total songs shipped on disk, many of which, in contrast to previous games, are master tracks. The Xbox 360 and PlayStation 3 versions also feature the ability to download additional songs. Several musicians appear in Guitar Hero 3, including Tom Morello (of the bands Rage Against the Machine and Audioslave) and Slash (of the bands Guns N' Roses and Velvet Revolver) as in-game characters. The PC, PlayStation 3, and Xbox 360 versions also include Bret Michaels (of the band Poison).

The game was well-received, though reviewers noted the difference in the feel of the game compared to the previous installments due to the change of developer. The game was the best-selling video game of 2007, both in terms of units sold and revenue earned.

Gameplay

The Guitar Hero III: Legends of Rock gameplay remains unchanged from previous titles in the series; the player must hit notes as they scroll towards the bottom of the screen in time with music in order to maintain their performance and to score points. Hitting notes using the guitar controller requires strumming the strum bar while holding down the correct fret button(s). Playing with the standard controller only requires the correct button to be pressed. Notes can be sustained (in which the fret button(s) must remain held until the note is complete) and can also form a chord (two or three notes played together; however the song "Go That Far" by the Bret Michaels Band features four note chords on the rhythm guitar track on expert difficulty. It is the first song that features four note chords in the Guitar Hero series; the Joe Perry Guitar Battle in Guitar Hero: Aerosmith and "Pride and Joy" in Guitar Hero: On Tour are the only other songs in the series which feature a four-note chord.). The game also simulates hammer-ons and pull-offs for sections with a rapid series of notes. Missing a note will cause a performance meter to drop; if this meter drops too low, the player will fail the song, represented in-game by the band being booed off the stage. A string of 10 consecutive correct notes earns a multiplier to increase the player's score (up until four times), and special sections, marked by starred notes, can be used to build Star Power; when released (by tilting the guitar controller up vertically or hitting a button on a standard controller), the player's multiplier is doubled, the performance meter increases faster when a correct note is hit, and there is less of a penalty for missing notes. As with the previous games in the series, Guitar Hero III contains four difficulty levels: Easy (which uses three of the fret buttons); Medium (which makes use of four of the fret buttons); Hard (which utilizes all five fret buttons); and Expert (which adds no new fret buttons, but increases the number of notes and the general difficulty).