From Wikipedia
Guitar Hero Encore: Rocks the 80s (titled Guitar Hero: Rocks the 80s in Europe) is a music video game and the third installment in the popular Guitar Hero series. It was released in July 2007 in North America and Europe, and in August 2007 in Australia.
Players use a guitar-shaped controller (purchased separately) to simulate playing rock music by hitting notes as they scroll towards the player. Rocks the 80s is an incremental title in the Guitar Hero series, rather than a full sequel. No changes in gameplay from Guitar Hero II have been introduced to this game. As implied by the game's title, the game features a 1980s theme, consisting of songs from the decade and playable characters, fashions, and artwork that reflect the time period.
The game was not as well-received as the prior two Guitar Hero games, due to the lack of new gameplay features and reduced soundtrack. Rocks the 80s is the third and final title in the Guitar Hero series to be developed by Harmonix before they moved on to create Rock Band. The next major installment of the series, Guitar Hero III: Legends of Rock, was developed by Activision's Neversoft division.