Oops! Sorry - wasn't even aware that there is something like official tags (Where can I find those?)
There is a misunderstanding here. Luminosity is not transparency.
I don't know any other word for it in English - it's "Leuchtkraft" in German.
There is a HLS-System (Hue, Luminosity, Saturation) for defining colors, just like there is the RGB Sytem.
What I have done for the demonstration was simply to replace the normal building picture with one
that had its luminosity reduced by 50%.
That is of course no solution because the building would show dimmed inside the game.
My hope was, that some code could be written to reduce the picture's luminosity "on the fly" just before
mixing it into the window background.
The other approach is perfectly doable: generate a "dimmed" version of all the buildings, store it together with
Menu.png and Idle.png and use this.
I will gladly volunteer for this, if it is going to be this solution.
@Alexia: I don't understand. What exactly is broken or buggy for you?.
For me the pictures look fine, they are only too bright and obscure a clear view on the wares.