When i tried out this mod in combination with "Space Exploration", i noticed that this fog of war will only work on the starting planet/surface but not on other vertical layers (due to "local surface = game.surfaces['nauvis']")

while game.surfaces['nauvis'] == game.surfaces[1], new surfaces created within the game will be game.surfaces[2], game.surfaces[3] and so on.

Suggestions:
1) Add support for multiple layers of surfaces
2) limit the calculation (to reduce lagg in MP) to active surfaces only or whatever game list suits the best performance-wise.

I can add an exception to Space Exploration surfaces, but some of surfaces must be without this mod, for example by Factorissimo2

Thanks for this topic, but I know how :)
Here is a lot of things for optimization, but not more than 1 check per tick makes a huge job.

Maybe you know but i don't know how to code all stuff i need for my mod :P

"some of surfaces must be without"
how about a tickbox in mod options? by default, only the base world is blacked and when the box is ticket, it will happen for all surfaces?

Easy solution, but i can have two mods with own surfaces, only one of them must have excepted.

So you say you create a second mod of this for multiple layers. people can then chose 1 of them, did i understand that correctly?

No, I will add all surfaces and then, if someone asks, I will add exceptions for some mods.

okay now i got it, thank you very much^^

Now it works without big lags, but some slower.

Suggestion on here, you could add a remote interface to whitelist surfaces which should have a black map

Yes, it's possible.