I haven't played this game yet, but as far as I can see are these HSB/HSL transitions (two of the tree values hue, saturation, luminance always stay constant when fading).

Unless thats wrong, I assume that it's done by a function, calculating HSB/HSL into RBG colors:

ex. in Java, assuming you are using java.awt.Color

Color c = Color.getHSBColor(hue, saturation, value);
String rgb = Integer.toHexString(c.getRGB());

Further a random number will be generated and one of these 3 HBL/HSL values will be changed to the generated value. Another number will be generated for the length of the transition.

I haven't played this game yet, but as far as I can see are these HSB/HSL transitions (two of the tree values hue, saturation, luminance always stay constant when fading).

Unless thats wrong, I assume that it's done by a function, calculating HSB/HSL into RBG colors:

ex. in Java, assuming you are using java.awt.Color

Color c = Color.getHSBColor(hue, saturation, value);
String rgb = Integer.toHexString(c.getRGB());

A random number will be generated and one of these 3 HBL/HSL values will be changed to the generated value. Another number will be generated for the length of the transition.