You need to use Unity Asset Explorer (UAE) to install this mod. There are plenty of tutorials on youtube on how to use it. There is a good chance that this texture doesn't work anymore though. It's pretty old.
A while after i released this texture, an update came out that reduced the file's soize from 700kb to 170. You can try using gimp or other programs to compress the .dds further if you really want to use this texture
11 comments