This page contains spoilers.
Overclock is an unlockable mode in N which basically speeds up all of the elements in the game (including the timer). It is unlocked when 6 columns in the main game are completed. It is toggled in the configuration menu, and has ten different settings. Generally, it is harder to play when overclock is on, and it can cause the game to lag. But, it can be fun, espiecially in race levels, and can be used to view highscores and DDA's at a greater speed.