The Heroic Legend of Eagarlnia Modding

[hilme]

hello there, so as the name say I am asking if someone can help me start making mod for The Heroic Legend of Eagarlnia game

 

game runs on Unity engine and I have manage to extract 2D art files from it using "Assets Bundle Extractor" tool and now I wanna repack or make a mod with my edited 2D art files to change some characters in that game but I don't know how so is there some tutorial on how to do it or something

 

is there some other tool I need