X-mod Effects

X-mod is a term culturally derived from DDR and StepMania, where the speed modifier is based on the BPM changes and stops, multiplied by a constant factor (x1, x2, etc. which is where the "X-" comes from). However, because of its implementation in these games, the BPM changes and stops are visible in the chart during gameplay. "X-mod effect" is simply the blanket term we use to describe any intentional manipulation of the scrolling speed (the speed that notes move towards the receptor) to facilitate some kind of choreographed effect or connotation. The reason why this is done is because sometimes the chart artist wants to utilize certain elements in the song that are otherwise difficult or impossible to follow with just notes.

General guidelines

Before creating a chart incorporating these X-mod effects, a notecharter needs to understand what constitutes as a fair effect. X-mod effects that are too ridiculous can be difficult or even impossible to hit on sightread, and this results in an unfair effect. This should be how the fairness of X-mod effects are judged: whether it is reasonable to hit on a sightread. A player who plays the chart for the first time should be able to clearly see and understand what is going on in the chart. Otherwise, a player will need to analyze the chart and memorize certain sections, which is tedious to do and generally not desirable as it is counter to the spirit of the game.

It is very easy to create an unfair X-mod effect as the thresholds are very constrained to begin with. Do not let a chart have a consistent speed that is more than approximately 1.5 times the base speed. Exceeding 1.5 times the normal speed for more than a couple of seconds will make it very difficult for the player to read due to the incredibly high speed. However, small bursts of higher speed could be acceptable, if there is some sort of indicator to prepare the player beforehand. Players all have their own preferred speed modifiers, but it is relatively standard for veteran players to play on a modifier that takes about 0.5 seconds between notes appearing on the screen to hitting the receptors. Average human reaction time is between 0.2 and 0.25 seconds, with 0.15 being the extreme outlier of possible reaction speeds. Keep this in mind when designing your higher speed sections.

Another guideline to follow that will for the most part ensure that the chart is fair is to place notes where they will be visually. For example, one could place a note on beat 1 and another on beat 2, but no matter what X-mod effects are applied between these two notes, the notes line up with the music on beats 1 and 2 respectively. This way, the player is completely prepared for any effects that he or she encounters, as the notes line up how they would be played normally. Of course, not all X-mod effects need to follow this guideline, but following it certainly helps, and it is almost a necessity for very effect-heavy sections.

Techniques

Adjusting the speed of an entire section is sometimes used to highten the difference in intensity. For example, a technique that is used quite frequently is to half the speed when the song reaches a calmer section such as a bridge, returning to the base speed when the song picks up again. However, this technique is not limited to just halving the speed. Using color manipulation schemes results in other speeds, while at the same time applying a change in color that might fit the song better.

A core technique to utilize is the stutter. The stutter is an effect where a stop occurs, followed by a very high speed so that the chart "catches up" to the player. This results in an effect that looks a lot like frames per second lag. The stutter can be used for entire sections of a piece as a theme. It is also effective for highlighting distortion or glitch effects in the background.

Musical elements that compliment well with X-mod effects include, but are not limited to: turntable scratches, silences or abrupt changes, glitch effects, volume or other properties that are applied to the entire song.