alpha {int}
If set to 1, this entity will be displayed with alpha transparency.
If set to 2, this entity will use negative alpha transparency (the darker colors are stronger, like shadows).
If set to 3, this entity will overlay transparency. It's described in the engine as being a combination of alpha and
negative alpha, and the formula is "bg<128 ? multiply(bg*2,fg) : screen((bg-128)*2,fg)".
If set to 4, this entity will use hardlight transparency. Seems to be the opposite of overlay. The formula is "fg<128 ?
multiply(fg*2,bg) : screen((fg-128)*2,bg)".
If set to 5, this entity uses dodge transparency. Described in the code as being "Very nice for a colourful boost of
light."
If set to 6, this entity will use 50% transparency. The entire entity will be 50% transparent: every pixel will be
averaged with the pixel right behind it.
In 8bit colormode, this setting DOES NOT work with remaps. You need 16bit or 32bit color mode to use this
together with remaps