But it was strange to have a redish skybox but having the Omega illuminate with green light...
In fact, you don't need to replace a existing skybox by yours... simply give a new number to it... and change the code in STAR_"color".entity ...
A little table :
Sun type ColoredSkybox DeepSpaceSkybox
RED 2,6 7
BLUE 2,4,5,6 7
YELLOW 2,4,5,6 7
GREEN 2,4,6 7
So, you can call your ColoredSkybox "8" and change in the STAR_red.entity
You will need to add a entry in SkyBoxProperties.skyboxbackdropdata too... it is there that you control the diffuse, ambient, specular, dust, galaxy color texture, etc...
By the way, i was not aware of it too... have just check the code now... it is your render who have make me think that skybox can be related to star type... and since almost everything can be found in entity file...
In fact, you can create a purple star if you wish and associate your own Skybox with it ... Sins is really great... it have some limit but almost everything can be fine tune... and code is always easy to understand... problem is mainly find the right file between the few thousand...
Remember, i am not a coder... so, maybe other file are involved too...
EDIT : Ue_Carbon was faster that me !!!