For example, sprites.lod contains the unit animations and the units themselves... All the animations in the game are hand-drawn... so adding units won't be a difficult task... EnglishT.lod contains the text files... the ones described
http://www.7wolf.ru/index_view_special_item_9278.zhtml
EnglishD.lod contains background images, buttons for the background menu, etc.
icons.lod contains armor, icons for game units, weapons, artifacts, etc.
So, with this program, you can create a pretty good mod...