I mod this game extensively, just never upload them. Ideally, to make a mod that affects only you, you want to create a custom "Ability", that you can then assign to your Civ, that becomes the key to any other changes you want to make. Such as:
- An improvement that only your Civ can create that gives you a colony bonus
- A Policy that only your Civ can select that give you the desired bonus
- Or you can bake the bonus into the ability
That requires:
- Data/Core
- Data/Gameplay Folder
- Data/GFX/RaceTrait
- Data/Text Folder
If you do it this way, you could possibly create one mod with a couple of "abilities" each one tailored to your needs. I created an Evil ability that super charges the bad guys to make things more interesting for me.
Regards,
Lawrence
