Hyperspeed
Set yourself up for a challenging game by making all of the songs go much faster than usual. This is a great way to practice songs if you plan on completing the game using the hardest difficulty setting. To enable Hyperspeed mode, press: Blue, Orange, Yellow, Orange, Blue, Orange, Yellow and Yellow at the main menu.
Unlock All Songs
Normally, you must play through the game on Career Mode to unlock songs, but you can use a cheat to unlock every song in the game for Quick Play Mode. To enable this cheat, press: Blue, Yellow, Orange, Red, Orange, Yellow, Red, Yellow, Red, Yellow, Red, Yellow, Red and Yellow at the main menu.
Performance Mode
Putting the game into Performance Mode means that the crowd's reaction has no effect on your game. This mode allows you to play through an entire song even if you aren't doing well, which is valuable for practicing songs without getting booed off stage. To enable Performance Mode, press: Blue, Blue, Yellow, Blue, Blue, Orange, Blue and Blue at the main menu.
Crowd Heads
Some of the cheats in Guitar Hero II don't affect gameplay, but are simply for fun. The following cheat codes will change what the audience members' heads look like.
To give the crowd eyeballs for heads, press: Yellow, Orange, Blue, Blue, Blue, Orange and Yellow at the main menu.
To give the crowd monkey heads, press: Orange, Yellow, Blue, Blue, Yellow, Orange, Blue and Blue at the main menu.
To give the crowd flaming heads, press: Orange, Yellow, Yellow, Orange, Yellow, Yellow, Orange, Yellow, Yellow, Blue, Yellow, Yellow, Blue, Yellow and Yellow at the main menu.
To give the crowd horse heads, press: Blue, Orange, Orange, Blue, Orange, Orange, Blue, Orange, Orange and Blue at the main menu.