Step 2
For this example I'm unlocking Getae. These are badic steps just to make the faction playable only. There are other steps should you want to make the faction more unique. There are 5 'files' that you need to edit to make this happen. Beside the campaigns folder as shown in above post you'll also need to extract faction_political_parties_junctions and political_parties from Rome II database (data_rome2) folder.
Check Rome 2 Basic Mods, Mod Compilations and Save Game Editing tutorial by Dresden if you're not familiar with extracting files.
Startpos changes.
CAMPAIGN_STARTPOS + CAMPAIGN_PREOPEN_MAP_INFO + CAMPAIGN_PLAYERS_SETUP + PLAYERS_ARRAY + (FACTION-NO) > CAMPAIGN_PLAYER_SETUP
Change the middle false to true.
CAMPAIGN_STARTPOS + CAMPAIGN_PREOPEN_MAP_INFO + FACTION_INFOS > (FACTION_INFOS-NO)
Change both false to true.
CAMPAIGN_STARTPOS + COMPRESSED_DATA + CAMPAIGN_ENV + CAMPAIGN_SETUP + CAMPAIGN_PLAYERS_SETUP + PLAYERS_ARRAY + PLAYERS_ARRAY-NO > CAMPAIGN_PLAYER_SETUP
Change the middle false to true.
You will see what you have changes turns into red colour. Save the file. Now we go to the final step.
DB changes.
Open political_parties table and add/clone 2 new rows to create 2 entries for your new factions. You can actually create your own unique faction trait under effectbundle column but that will need a whole new tutorial for that. For this tutorial just copy any existing vanilla traits from other factions. For Getae I choose Epirus as I think they're the nearest.
Fimal step, open faction_political_parties_junctions and add/clone 2 new rows to create 2 entries for your new factions. The entry in the politicalparty_key must be the same name as in political_parties table that you have edited earlier.
Save and run you mod with the mod manager.