Why are some Wii U games in red cases?

Does anyone know why some Wii U games have red cases? There doesn't really seem to be any reason for there to be. Mario Kart 8 had it, and now Super Mario 3D World is being rereleased with the red case as well. Is it just because they're Mario and Mario's main color is red? I don't think it looks as good as the blue cases since they're keeping the blue Wii U logo.

I think that Nintendo is trying to put the games that will sell good in red boxes so that they stand out and I can also see Smash Bros Wii U getting a red case at some point.

Hmm I wonder about something.. Ah ha, I was right. Hehe; according to a blog I found color affects how people purchase things.

Red: The color red increases heart rate & creates the need of urgency. sauce 

Here's another example of the same color on another site I found;

RED. Physical
Positive: Physical courage, strength, warmth, energy, basic survival, 'fight or flight', stimulation, masculinity, excitement.
Negative: Defiance, aggression, visual impact, strain.

Being the longest wavelength, red is a powerful color. Although not technically the most visible, it has the property of appearing to be nearer than it is and therefore it grabs our attention first. Hence its effectiveness in traffic lights the world over. Its effect is physical; it stimulates us and raises the pulse rate, giving the impression that time is passing faster than it is. It relates to the masculine principle and can activate the "fight or flight" instinct. Red is strong, and very basic. Pure red is the simplest color, with no subtlety. It is stimulating and lively, very friendly. At the same time, it can be perceived as demanding and aggressive. sauce

So it looks to me that the color red on some level or another is being used to try to persuade the buyer into buying said item with it's color thus why some Wii U games are in the red color.

It's freaking Mario. Clearly it's the blood he's shed over the years. The Wii version of NSMB was red as well but I can't remember if anything else was too. He's a prizefighter.

They stand out more.
Plus the fact, well it's Mario....
If you look into a bunch of Wii I games, the red cases stand out.

Yeah it probably is just that they stand out more. But maybe they did choose that specific color because of what Queen said. I do wonder why only Mario games are in the red cases though, if that's true.