I'm wondering if there is a way to limit the metal amount on moons to 5-10 spots. At the moment I'm having more fun playing on planets that have metal only on spawning site, I achieve this by setting the metal density to 0 or a negative number. Unlucky I couldn't find a way to put few spots outside of the spawning point, rising the density or clusters even to really low numerbers makes metal appear all over. At the moment is impossible to balance metal on moons, either I get moon with 0 metal if i put 0 or a negative number (I don;t want spawning points on moons), or I get tons of metal even putting the amount to low numbers (ie. 1-10 on a scale of hundreds). I think this must be a bug or something like that, because of this at the moment is impossible to balance mass between the starting planet and the moons.
You could try leaving the metal density at normal, and set clustering to be really high. I know Spawn Wars games set clustering to 200. To test configurations, you could make a system with a bunch of differently configured moons (with names corresponding to their configuration), so you only have to play it once to see how they all turned out.
IIRC you can set metal density to a negative value to get low metal density. Try somewhere from -60 or -80. It's silly that metal density is non-continuous from 0.
As I already said values of 0 and negative values make metal disappear from moons. Problema is that metal has only a binary behavior, either there is tons of metal or there is nothing, this for moons or planets without spawning points. Instead on planets with spawning point 0 or negative corresponds to 5 metal spots on each spawning point. This creates a total unbalance on games, it is always convenient to go on moons with metal, turtle there and then kill the others starting with the main planets (harder to defends cause of the size).
in system editor you should be able to see the metal generated on each planet. It is too inconvenient to have to test the system in a match or with AI.
It's not impossible Go have a look on the exodus system sharing for examples Tanis is the favourite moon of many top players. The multi-planet systems in there have a 0 metal smashable ...