Warning: The following advice is for experienced modders and can seriously damage your game if used incorrectly. It is a very high level explanation, and if you do not understand it at this level of detail you probably shouldn't try it! I strongly advise that you back up your (xpack)language.dll, techtree(x).xml, majorgods.xml and any other file you change before attempting it.
I have got around the compatibility issues by creating a new version of the .exe that uses different names for the key data, language files and AI files, so none of the changes affect the standard game. If there is sufficient interest I will post it.
INTRODUCTION
Before embarking on the process of creating a new major god it is important to understand the structure of Age of Mythology. AoM:TT comprises 4 cultures (hard-coded), 12 civilisations (hard-coded to the extent you can only have 12), 12 Major Gods - one for each civilisation and 36 minor gods (9 for each culture).
Also remember that a Major God within AoM is used both as an Age 1 technology - e.g. Age 1 Zeus and a Civilisation - e.g. Zeus. As an Age 1 Technology, a major god can be modified in the same way that any technology can be changed, however as a civilisation many aspects are controlled by the game's .exe (such as all the associated gadgets used in the set up menus). The AI also uses references to the civilisations, Major Gods and Minor Gods. These areas cannot be easily changed without access to the source code.
Within these contraints the following is the easiest way to add a new Major God.
ADDING A MAJOR GOD
1)Decide which existing Major God you want to replace.
2)Edit the fields in the language.dll or xpacklanguage.dll that refer to this unit, the text for Major and Minor God entries will have the following format:
Major God Name Note: Athena is both a god and a character, so check the protox definition for Athena to avoid changing this characters name. When you are done save it. If you want this god to be part of a new culture, do a text edit on whichever culture you want to replace (Greek, Egyptian, Norse, Atlantean) and change this accordingly. If your not sure of the text id, just check the uigodpicker.xml file as this includes all the relevant text references. Note: All you have done here is changed the names displayed during the game. 3)Start-up the game and check that the new Major Gods name appears (and new Culture if changed)on the uigodpicker screen. You may also want to change the roll-over text for the gods as well (e.g. this god helps your xyz). Just search for the existing text in the (xpack)language.dll and change it. Note that when you select this god it will still call the original Age 1 Major God tech. 4)Open the majorgods.xml file and you will see that each major god has a series of portraits defined. These are reducing in size versions of the same picture. Convert one of the original 256x256 portraits to bitmap format (you'll find them in the textures/ui folder) and use this as a basis of your new god format. Save the file as "ui god newname 256x256.bmp" and then shrink it to make 128x128, 64x64 and 32x32 versions. Convert these to .DDT and put them in your texture\ui folder. You will also need 128x128 and 64x64 unframed portraits (find the originals in the texture\icons folder - file name God Major XX Icon ZZ). Once you have done this edit the majorgods.xml file to reflect the new portrait names and convert it to .XMB format in you \data folder. 5)Reload the game again and you should now see the new icon(s). 6)Open techtreex.xml and go to the appropriate Age 1 Major God tech and change its < 7)Open the faketechtreex.xml and find the relevant references to the Major God you have changed and change the icon and text references accordingly. Save it and convert it to .xmb format. You now have a new Major God. Hope this helps.
Minor God Name
WORSHIP Major God
WORSHIP Minor God
Your have advanced to <
% advances to the <
Just replace the existing Major God name (Zeus, Hades, Isis, etc.) with your new name.
From here on it is just standard techtree editing (eg. change the <