Welcome to the world of modding! Congratulations and condolences.
LeeS has put together a great starting point for new modders
here. Check out post number 3 on using logging to help troubleshoot errors.
In your Secret Base file, there are a couple of errors. First off, you have <GameData> twice:
Code:
<GameData>
<GameData>
<Buildings>
<Row>
.
.
Secondly, you have mixed up the BuildingClass and Type. I presume you want the Secret Base to replace the Palace. It should be:
Code:
<Buildings>
<Row>
<Type>BUILDING_[COLOR="Red"]SECRET_BASE[/COLOR]</Type>
<BuildingClass>BUILDINGCLASS_[COLOR="red"]PALACE[/COLOR]</BuildingClass>
<ArtDefineTag>[COLOR="Blue"]SECRET_BASE[/COLOR]</ArtDefineTag>
</Row>
</Buildings>
The ArtDefineTag above should match the standard Palace.
The BlueRogues file is missing a number of standard elements, such as the tables defining building- and unit-class overrides, assigning the leader to the civ, etc. Please see LeeS's guide to find "XML data files for Standard Civilizations (inc DLC) tutorial (by whoward69)" for examples.
I don't see where you've defined the leader trait "Gold from Kills" unless I missed it, so the trait won't do anything (and may cause the whole file to discard).
Some of your TXT_KEY entries say BLUE_ROGUES and some say BLUE_ROGUES
S, you'll want to sort that out.
There may be other errors, too, but this should get you started. Best of luck, and don't get discouraged!