Axis Football 2015 comes with basic roster mod support, and our first update (scheduled for mid August) will feature additional layers of modding (player stats and team uniforms).
If you would like to modify the rosters in the game, simply follow these steps:
1) Right-click on the game (Axis Football 2015) in your Steam library.
2) Selection 'Properties'
3) Click on the 'Local Files' tab
4) Click on the 'Browse Local Files' button
5) Open the 'Rosters' folder
6) Find the .txt document for the team you want to edit
7) Change out the player name, number, or race.
8) Save the file and launch the game
A few notes:
1) Do not edit the positions. Those aren't read into the game, they're there for you to see which player you're editing
2) Don't remove the *. Those are needed as delimiters so that the game can separate the information when it's parsed in.
3) I would strongly suggest keeping a backup of the rosters in the event that you screw something up. Worst case scenario, just redownload the game to get the default rosters back.