- It must be saved into a PNG format.
- It can only consist of 1 layer. If you use more the game will crash upon importing it. Make sure you flatten/merge the layers on the image before saving it.
- The image must be saved/edited in grayscale mode and cannot consist of or use colours.
- The Image Size should be even on both size, the standard size is 513 x 513 pixels.
- The use of "Alpha Channel" should be left unmarked/turned off.
Also, make sure there aren't any spaces in the file name.