Adding a Custom Menu Item - notweuz/FNF-OSEngine GitHub Wiki
Files you need.
For creating custom menu item you need:
- Button spritelist
- menuitems.txt file
Setting up.
Create a menuitems.txt and put it in the mods/my-mod/data folder, currently it supports only adding one item. File should look like this:
name||link
Make sure there's only 1 line in file.

^^^ Example
Also you need to add spritelist for it. Put it in the mods/my-mod/images/mainmenu and name it like
menu_name

^^^ Example
Finish
If you did anything right, there will appear new button.

Note: Your mod should be on top of other mods, or button won't appear.