As with previous games in the series, Guitar Hero: Warriors of Rock is a rhythm game, allowing up to four people play in a band on vocals, lead and bass/rhythm guitar, and drums, to use special instrument controllers to simulate the playing of rock music.[5][6] In general, the goal for each player is to match scrolling note gems that correspond to that instrument's part in the given song to score points; the guitar and bass player must hold down the appropriate colored buttons on the controller and then use the strum bar as the notes pass over a marked zone; the drummer must strike the matching drum pads on the controller when the notes pass, and the vocalist must match the relative pitch of the song's lyrics as guided by phrase markers. Successfully striking notes earns points and boosts the player's performance meter; missing notes will cause this meter to drop. When playing by one's self, if the performance meter should empty, the song will end and require the player to restart it; when playing in a band, the remaining band members must play well enough for a limited time to "revive" a player that has fallen out due to an empty performance meter, or else the whole band will fail the song. Prior to the start of a song, each player can select one of five difficulty levels: Beginner, Easy, Medium, Hard, and Expert, with a sixth difficulty of Expert+ available to some songs on the drums which introduces a double bass pedal. Harder difficulties have characters with high note densities and more difficult playing techniques; each player can select their own difficulty to play.
For guitar and bass players, the players are given the opportunity to play single notes or chords, both as single notes or sustained, during which the players must continue to hold down the fret button(s) for the extent of the sustain. Some charts provide the ability to hold down one sustained note via its fret button while strumming additional notes. Warriors of Rock also provides simulated hammer-ons and pull-offs, where, after striking one note, specifically marked notes can be played by fingering the correct buttons but without strumming. There are also note portions of some songs where notes appear semi-transparent relative to normal notes; these notes, introduced in Guitar Hero World Tour, can be played simply by tapping the correct buttons on the controller without strumming or using a touch-sensitive "slider bar" below the fret buttons, if the player is using a World Tour controller. Bass players can play open chords by strumming without holding any fret buttons. Warriors of Rock introduces sustained open chords for bass players, although unlike other sustainable notes, does not require you to hold down the button required to execute the note initially.[7] Drum players, when using velocity-sensitive drum kits, may be presented with both ghosted notes or notes with a shield icon over them; these represents drum notes that should be struck softer or harder than normal, respectively, to score more points. Drum players can also attach a second bass drum pedal, necessary for certain songs in the "Expert+" difficulty.
If the player successfully matches a number of consecutive notes correctly, they boost their individual scoring multiplier up to a maximum 4x value; missing a note will reset to the multiplier back to 1x. Throughout each song's respective charts for the instruments are special highlighted phrases; completing all the notes in this phrase, and for guitar/bass players, using the whammy bar on marked sustained notes, fills part of a Star Power meter. When this meter is at least half full, the player can activate Star Power by performing special actions on their controllers: either tilting the guitar controller upward briefly or pressing the Star Power activation button for guitar and bass; striking two pads simultaneously on the drums; and either double tapping the microphone or pressing one of the buttons on the game console's regular controllers for vocals. When Star Power is activated, the overall band scoring multiplier is increased for a limited time until the Star Power meter is drained. After completing a song, the band is awarded a number of stars based on the overall score; in normal modes for Warriors of Rock, up to six stars can be earned; the final being achievable only through zero misses and zero extra strums.
