I'm prepping for a Unity 3D Certification, and one area it will ask about is "Unifying Color". My assumption on this is that it is referring to a theme of colors, or the color palette, to help bring focus to particular moods or intensities. For instance, bright vibrant/contrasting colors to promote an energetic feel, or using cool pastels and off whites to promote a feeling of distance and openness.

My google searches turned up lots of examples, but no clear definition. Perhaps my understanding is wrong, and I really am hoping for a more concise definition

Thanks in advance for any help or conversation on it. I'd really like to get a variety of perspectives on this.

- Thanks!

Well, in the context of Unity I really have no idea. If we were talking about fashion design, it would be a color that's used in many small areas on most or all articles of clothing that make up an outfit; like you could have a red and white jacket with gold buttons, blue pants with gold piping, and white sneakers with gold laces, and gold would be the unifying color.

I guess in some cases if you are using colored lighting, the color of the lighting could be a unifying color? For possibly related terms, I've heard of color palettes having a "central color" - that's defined mainly in the negative, by the fact that all colors that clash with the central color are forbidden from the palette. The flesh tone of the main character would be an obvious candidate for a central color. And another thing I've heard of is a "key color" or "identifying color" - that's the one which is rotated or substituted to visually distinguish between different factions, settings, or monster variants.

It's unclear what they mean with just "unifying colour".
If it's related to colour harmony then I would study the different hue arrangements that you can find with a colour wheel. I don't remember any excellent resource on hue relationships on the wheel except for that Dota 2 article by Valve, there's a section on this:
http://media.steampowered.com/apps/dota2/workshop/Dota2CharacterArtGuide.pdf

I would also look into:
- gamut masking, a tool that you use when picking colours for painting.
http://gurneyjourney.blogspot.com.br/2011/09/part-3-gamut-masking-method.html

- gamut mapping, when you already have an image and want to convert it for display in a different output, but you can also use this to unify the colours from the original in a creative way by specifying a custom gamut like what you would do with the masking above.
http://handprint.com/HP/WCL/color11.html#paintzone

- the "gradient map" algorithm or filter, replacing colours based on some measurable brightness value (usually the HSB brightness value). You can use a soft opacity (a linear combination) of the original and gradient map versions so the effect is subtle and the original colours still remain, but are drawn closer together (unified):
http://www.premiumbeat.com/blog/gradient-maps-and-blend-modes-in-after-effects/

- anything that explains cinematic colour grading.