A light map can give off lighting similar to my Wario Colosseum track. These are used in Splatoon and Mario Kart 8, and many more.
These maps are quite simple. You have the light color for the rgb data. Then alpha controls fading/intensity. The process is mostly the same from our ambient occlusion tutorial so feel free to skip to the bake options below if you know all of this.
First lets start by making our second UV map.
Press the tab key to go into edit mode, and press U and Smart UV project.
Then set the Island Margin to 0.05. You can make it larger if necessary but smaller can give a larger area for the islands.
This is to give our UVs some space for the baking process. You may need to experiment with unwrapping more later depending on your model.
Now lets check our UVs. Make sure that UV that was added before is selected. Now drag the window on the right to create our UV window.
Like this
So now we can see our UVs. We want to now add a texture to bake on
For the settings window, the width and height can be important as a higher size can give better quality but be slower at baking. For now we will keep it this size. We can resize it to be smaller later if we need to for in game.
Before we begin baking, make sure to hide any models you don't want as i have done here (one we want to show is in blue)
Bake with lights : Option 1
To create these, simply setup a scene with lights using Shift + A and Lamps. For this tutorial i will be using points. Make sure you are in material view for previewing.
Uncheck "Specular" option. Change the color to whatever you want.
Now to begin our baking process. Go ahead to the camera tab and use the "Full Render".
Press the bake button. This will now bake the lights to the texture! While they may seem very basic, mario kart 8's also are quite simple. You don't need to worry much about detail.
Now save the texture once you think it's ready.
For fading use a program like paint dot net or some other image editor. Make your image black and white/grayscale.
Adjust the brightness and contrast for the intensity you want.
Save this as a separate image. You will need to combine both after.