The files for this game has no compress and no encryption. Not only music, but you can also replace any texture you want.
Because I don't know how to compose, I find free music online for publishing on Steam. When it comes to quality, I think these are not so good. However, during testing, we did find people that love those music.
Anyway, we are here to share methods for replacing music in the game.
First, find your Steam Library. This is different for everyone, but at default it should be with the Steam Store software.
For the default situation, the game path will be: \ steamapps \ common \ War Ender Evolution
And the music file is in: \ res \ audio
You will need to convert your music into the same file type and change the name to the same as the one that you want to replace. Then you can duplicate the file you want into that folder and make the replace happen.
Just a reminder, music in selection menu auto loops and there is no limitation on duration, while stage music and boss theme do not loop. The stage is 160 seconds long, and the boss fight is 120 seconds long if keep shooting.