if a module’s effectiveness goes down, what exactly goes down? it’s hitpoints? it’s strength? (shields) everything? (a bit)
I think it only applies to shields an armor. Basically you get less damage absorption from your shields and less armor thickness increase per armor module if you use more than one. Shield resistance stays the same I think.
I’m not sure if damage absorption for armor is reduced when you add more modules though.
For armor and shields, you can tell exactly what you’re getting by looking at the “armor thickness” / “shield strength” summary. The stacking efficiency goes against these numbers (and nothing else). The reason for the stacking efficiency is that without it ships would be better off choosing either shields OR armor but NOT both. With diminishing returns, it becomes needed to balance the two, as originally intended.
I don’t see the point of balancing armor and shields the way the game mechanics currently work. In the majority of cases, armor only needs to be sufficient to prevent your cruisers from being chewed up by laser fighters. If you’re not building an armor tank, shields are a far more cost-effective defence. Once your shields are down, cruisers are dead meat with or without armor unless your opponent left all his anti-armor weapons at the spaceport.