Assuming you have BTS, these are the minimum files you need to change (some say the "schema" files, but these files will do just fine... I've never once changed a schema file).
The below files can be found in either default or BtS XML folders... copy them into custom assets or a mod folder before making changes.
Minimum XML files to add a leaderhead:
--------------------------------------
1) Civ4ArtDefines_Leaderhead.xml
2) Civ4CivilizationInfos.xml
3) Civ4LeaderHeadInfos.xml
4) Civ4GameText_Civilopedia_BTS.xml
5) Civ4GameText_Objects_BTS.xml
1) Civ4ArtDefines_Leaderhead.xml
Should look something like this:
Code:
<LeaderheadArtInfo>
<Type>ART_DEF_LEADER_CALIGULA</Type>
<Button>Art/Interface/Buttons/LeaderHeads/Caligula.dds</Button>
<NIF>art/LeaderHeads/Caligula/Pacal.nif</NIF>
<KFM>art/LeaderHeads/Caligula/Pacal.kfm</KFM>
<NoShaderNIF>art/LeaderHeads/Caligula/Pacal.nif</NoShaderNIF>
<BackgroundKFM>art/LeaderHeads/Caligula/Pacal_bg.kfm</BackgroundKFM>
</LeaderheadArtInfo>
One of the most important things to modify... make sure the NIF and ART lines match the paths and file names for the custom files you've downloaded.
2) Civ4CivilizationInfos.xml
Pretty small entry... look for other leaders, then add something like this:
Code:
<Leader>
<LeaderName>LEADER_CALIGULA</LeaderName>
<bLeaderAvailability>1</bLeaderAvailability>
</Leader>
3) Civ4LeaderHeadInfos.xml
This is by far the largest/trickiest to work with. I won't post the whole code, but simply-put, find a leader with similar traits... if you think Caligula would be most like Ghengis Khan, copy Ghengis Khan's entry... or if you thought he'd be most like Pacal... copy Pacal's entry... so-on and so-on. It's a very large entry, so copy the WHOLE thing. You need to change at a minimum the first few lines... I'll post that snippet here:
Code:
<Type>LEADER_CALIGULA</Type>
<Description>TXT_KEY_LEADER_CALIGULA</Description>
<Civilopedia>TXT_KEY_LEADER_CALIGULA_PEDIA</Civilopedia>
<ArtDefineTag>ART_DEF_LEADER_CALIGULA</ArtDefineTag>
Note the lines you use in the above code must match the lines you are putting in the other files you're altering. Below the first major block of code lines you'll find the "Trait" and "Favorite Civic" lines... those are pretty easy to change if/when you want to.
You'll also probably want to change the "<DiplomacyMusicPeace>" code section, as this matches civ/leader music... if you copied Ghengis Khan's leader entry for Caligula for-instance, you'll get rather oriental music in the game for your Roman Caligula if you don't change this section... simply cut/paste from the right civ/leader for this area (say Caesar) if you want the music to make sense... though this is not mandatory to make a leader work, it's recomended.
Remember... the above code determines the leaders personality in-game, so it's important to copy/base your new LH code from a leader with similar traits... if you're adding a new LH to the game that is very belligerant and war-like, you would NOT copy Ghandi's LH code!
4) Civ4GameText_Civilopedia_BTS.xml
I'm not going to say much about this... simply-put, it's what you change/add to create the Pedia entry for your LH... if you're incredibly lazy, you can re-use an existing leader, but I recomend doing something here... at least copy a Wikipedia bio or something! Copy an existing LH pedia entry if you need help with formatting here.
5) Civ4GameText_Objects_BTS.xml
Add some simple code for using the appropriate LH name... something like this:
Code:
<TEXT>
<Tag>TXT_KEY_LEADER_CALIGULA</Tag>
<English>Caligula</English>
<French>
<Text>Caligula</Text>
<Gender>Male</Gender>
<Plural>0</Plural>
</French>
<German>
<Text>Caligula</Text>
<Gender>Male</Gender>
<Plural>0</Plural>
</German>
<Italian>
<Text>Caligula</Text>
<Gender>Male</Gender>
<Plural>0</Plural>
</Italian>
<Spanish>
<Text>Caligula</Text>
<Gender>Male</Gender>
<Plural>0</Plural>
</Spanish>
</TEXT>
