This tutorial is obviously created for those who have never modded warscape before. There are many ways and possibly other tools to mod this but I'm using Pack File Manager because that's the one I'm familiar with and find it easy to use.

To start, please download Pack File Manager
http://www.twcenter.net/forums/showthread.php?618353-PFM-3-0-3-Added-option-to-have-csv-replace-data.

It's good to also read Warscape Modding Premier by daniu.
http://www.twcenter.net/forums/showthread.php?620537-Warscape-Modding-Primer.

Once you have an idea how it works then it is time to start with modding the simplest thing of all, increasing turns per year.

First create a folder (I use desktop for easier access) for all modding work and go to your Rome II data folder and copy campaigns folder. It depends on where your game is installed but the default location is C:\Program Files (x86)\Steam\SteamApps\common\Total War Rome II\data which contain folders called main_rome and 3 prologue folders. You can delete the prologue folders if you only want to mod the main campaign. You are going to edit the startpos.esf which is located inside the main_rome folder.



Now run PFM and enter you mod name (or you can use the default my_mod). Once you my_mod.pack is safely created it will be time to add the startpos.esf to your mod.

Your mod folder should now look likes this.



I have always set up that the pack files be open by PFM so that I can immediately open any pack files I want to edit rather than opening PFM files and selecting files which I want to mod.

Right click on my_mod.pack > Add > Directory as shown in the picture below.



Browse to where you have copied your campaigns folder (in my case inside Tutorial folder on desktop) and click OK. You'll see the green campaigns/main_rome/startpos.esf as shown below.



Now the easy part is to click on startpos.esf in the left column which will open a middle column. Clicking on the (+) sign will open up 3 more options where you need to open up COMPRESSED DATA > CAMPAIGN_ENV and then click on the CAMPAIGN_CALENDAR. On the 3rd column you'll see Value (1) which you can change to increase the turns per year. I have no idea what's the max number yet but you can test any numbers you want (2 to 12 should not cause any problems). Once you make any changes to the number it will turn into red.

See below for details.



Now you can save the file (or use save_as if you want to rename) and put this inside Rome II data folder. I would suggest to use Mod Manager (and make sure to use the default Mod type) for your pack file so that you can revert back to vanilla or merge with other Mod type pack files easily.

Now it's done !

Note: This only change the turns per year. You can also edit other files top increase the build times and possibly research time and add them to your mod file. If there's no tutorials on this I may create them later.