The Color / Blending Settings control how the particle color and transparency behave over the particle lifespan.

Color / Blending
Color
Color Timeline Gradient	Sets the how the color changes across the lifespan of a particle. The color values are multiplied to the texture color values. Therefore setting a white color here, will result in the texture colors being used.
Position	Sets the percentage position of the timeline node
Opacity
Opacity Timeline Gradient	Sets the how the Opacity changes across the lifespan of a particle. The opacity values are multiplied to the texture opacity values, therefore any transparency set by the assigned textures will be respected.
Position	Sets the percentage position of the timeline node
Alpha Blending
Source Method, End Method	This is where you define how your particle is going to be blending with the scene. Bright Engine supports all OpenGL blending methods and so you have a plethora of combinations which you can use to create the desired effect. By default your particles will be GL_SRC_ALPHA and GL_ONE. This is called additive blending and is ideal for effects like fire but not so much for something like smoke. See what combinations work for your effects! (If you would like to understand how each of the options differ, you can find full descriptions from the OpenGL documentation)
Sort Particles	Some Blending methods are order independent, which means the order in which they are drawn is irrelevant. In this case this setting should be disabled. However for Blending methods which are not order independent, you can enable this setting to make sure that the particles are drawn in order of distance to the camera (furthest first, closest last.