To install this skin, extract the files in the zip file to the folder /Android/data/nl.joriswit.soko/files/skins/heavymetal/ on your internal SD card.
Soko++ for Android has limited support for custom skins. All subfolders of /Android/data/nl.joriswit.soko/files/skins/ are assumed to contain skin images.
HeavyMetal skin
To install this skin, extract the files in the zip file to the folder /Android/data/nl.joriswit.soko/files/skins/heavymetal/ on your internal SD card.
You can also create your own skins. All images need to have a specific name. I recommend to look at the Heavy Metal skin to see the filenames of all tiles. The mover_store.png and object_store.png images are optional (the two default skins do not use such a image). All other files are required. All images must be 50x50 pixels.