The core gameplay in Rock Band 2 is mostly unchanged from the original Rock Band. Players use controllers modeled after musical instruments to simulate the performance of rock songs. Players use these instruments to play scrolling musical "notes" on-screen in time with the music. Rock Band 2 offers single-player and multiplayer gameplay for lead guitar, bass guitar, drums, and vocals, allowing for any combination of parts to play as a band.
During song performances, the game displays up to three tracks of vertically scrolling colored music notes, one section each for lead guitar, drums, and bass. The colored notes on-screen correspond to buttons on the guitar and drum peripherals. For lead and bass guitar, players play their notes by holding down colored fret buttons on the guitar peripheral and pushing the controller's strum bar; for drums, players must strike the matching colored drumhead, or step on the pedal to simulate playing bass drum notes. Along the top of the screen is the vocals display, which scrolls horizontally. The lyrics display beneath green bars, which represent the pitch of the individual vocal elements. When singing vocals, the player must sing in relative pitch to the original vocals. A pitch indicator displays the singer's accuracy relative to the original pitch. The remainder of the screen is used to display the band's virtual characters as they perform in concert.