After picking a song to play, each player has the option of enabling various modifiers that will effect the note chart they're presented with.
Different play modes offer their own sets of modifiers:
Strums and Hammer-Ons/Pull-Offs are converted to Tap notes.
Useful if one doesn't want to strum anything, or to aproximate Keys gameplay.
Strums and Taps are converted to Hammer-On/Pull-Off notes.
Helps you avoid strumming so long as you maintain your combo.
Hammer-Ons/Pull-Offs and Tabs are converted to Strum notes.
Strum everything. Evocative of the first Hero game.
Hammer-Ons/Pull-Offs are converted to Tap notes.
Still gotta strum the Strums, but the rest is more lenient.
Taps are converted to Hammer-Ons/Pull-Offs.
Still gotta strum the strums, and the rest demand combo.
Strips out the bass pedal, leaving you to just hit the pads and cymbals.
Lets you play with a peripheral that doesn't have a pedal, or just focus on your stick work.
Turns the whole song to talkies, for a more free-form performance.
Wanna rap your way through a ballad? Have at it!
Removes any Vocal Percussion notes that may be in the chart.
Handy for folks singing with another instrument in their hands, or for those who just don't wanna smack their microphone.