overall higher maximum difficulty cap for Nightmare Mode. Exceed 2 added the infamous "????" rating for unusually difficult songs. This level is often referred to as "unrated". Many unrated songs are more difficult than the allowed maximum. All "another" rated songs given a level of "??" in Exceed 2. Later games have most "another" step songs show a numeric difficulty instead of question marks. Unrated songs often feature gimmicks, experimental charts, or are not made to be beaten by a single player and are not recommended for the average player. Another rating charts vary in difficulty and can be easy, however, they are typically harder than the regular chart of the song at a similar level. Early games up to Zero and including the New Xenesis series showed the levels via icons. These games use a star scale to measure the lower levels, which goes up to 8 in half increments (for a maximum level of 16). The higher levels are measure by a skull scale which goes up to 8 in whole increments. On NX2 and NX Absolute, the difficulty scale is modified with a line of circles that go up to 8 in whole increments. Higher difficulties replace these circles with stars and even higher difficulties replace the stars with skulls. Starting with Fiesta, the Normal / Hard / Crazy / Freestyle / Nightmare modes are replaced by prefixing the difficulty level before the difficulty number. Another difficulty charts are placed among the regular charts for the song and are prefixed with "Another" instead of a difficulty level, though this was removed between Fiesta and Prime. Modifiers Since the first release, all game modes accept modifiers which are enabled by using special codes inputted by rapidly stepping on the gamepad. The effects vary from speeding arrows up, changing the design of the arrows altogether, making them fade as they go up, or making them appear in random places instead of their pre-defined column (while still being on the same beat). Most players after a starting period get used to applying the modifiers to make arrows faster which makes them more spaced out. All songs have a default speed of 2x. It is also possible to decrease the arrow speed. Using modifiers a matter of personal preferences even though the increased speed options are very popular, especially at higher levels where there are many arrows on the screen at