What I’m searching for is some guidelines to make my game moddble since day 0.
E.g.: Instead of “hard-code” a new map in the game code, why not doing it already as a mod? Same for new races, enemy types, resources, items, etc.
Let’s say you hire a level designer. Give him your modding tools directly instead of having to give him access to full source.
I think this is one of the pillars to develop a game the right way since day 0.