The color and composition of an effect is as important as its timing or scale. Color and opacity determine visibility to the player and provide feedback about the source and content of an effect. The player expects certain effects to be specific colors, such as a damaging poison cloud being green in color.
Visual distinction (or lack thereof) from other effects and the game world can be controlled through color. The composition of an effect should contain a range of colors where appropriate. Effects without a range of colors look flat to the user and lack a sense of depth, which can be used to advantage where appropriate. Most real life events replicated through effects contain a range of values and colors broader than initially thought.
One of the key aspects of composition is the order in which particles sort against each other and the blend modes used on the particle art. Often one will want particles with additive shaders to sort in front of alpha-blended particles. An example of this is a muzzle flash on a rapid firing weapon: the lingering alpha-blended smoke from a previous shot will cover up the powerful additive flash from a newer shot.