Skin Image
To make a skin file you must first create an image file. This must be a PNG file that should have an alpha layer. The alpha layer can give the image partial transparency. This reduces the number of separate images needed and gives a much better looking end result. The skin image will contain all the square images needed to make a complete skin. The images are placed side by side.

The size of each image can be any number of pixels, but a size around 100x100 is reasonable. A larger size gives nicer graphics but larger skin file and a smaller size doesn't look so good when enlarged. You can use any image editor (Photoshop, PaintShop or any other) to create the skin image.

The total number of images needed depends on the following choices:

• Floor: Two images, one for plain floor and one for goal.
• Package: One or two images, one for package on floor and optionally one for package on goal.
• Sokoban: There are several choices for the Sokoban himself. One single image or four images, one for each move direction, or one image facing front and the four for moving. This can be complemented with four images for pushing in every direction. Each of the above mentioned can also be complemented with the same image(s) over a goal.
• Wall: One or sixteen images. One for simple walls or sixteen for connecting walls. In the case of connecting walls one more image can be used to cover the top of four neighboring walls (see Wall Top below).

The order of the images is not important. The Classic 2 skin looks like this in the skin tool.



Transparency
The images can be made transparent using an alpha channel, this is especially useful for the package and Sokoban images. When a package or Sokoban passes from floor to goal and is halfway between, it looks much nicer if the image is transparent. Transparency also reduces the number of images needed. If the Sokoban image is transparent, the same image can be used for Sokoban on floor and on goal. Note the checkered background of transparent images.

Wall Top
The Wall Top image is used to cover the hole that appears when four walls are placed in a square. The left image is without Wall Top and the right is with. Wall_Top_X specifies how much to offset the image to the right and the Wall_Top_Y gives the offset downwards.

Background Image
The background is what is shown around and outside the actual level. It can be specified with the Outside parameter which indicates one of the pictures in the Skin image.

A background can also be a separarate image with a different (larger) size than the pictures in the skin image. Use the Assign External Background function to include a background image and the Embed External Background function to make it embedded in the skin file. The background should be a tiling picture.

Skin Tool
The skin file is a text file. It can be created with any text editor, but easiest is to use the Skin Tool. Use New or New from Template to create a new skin file. You can also open an existing skin file and use Save As to give it a new name and then start to modify it. Now, you must assign the image you created. Make sure you saved your image in the same folder as the skin file. Use Assign External Skin to connect the image with the skin file. Please note, that the skin now consists of two files, the skin file and the image file. It is a good idea to have the image external during the design of the skin, this makes it easy to modify the image, save it and immediately run the game and see how the skin looks.

When you are satisfied with the design of your skin you should use Embed External Skin to embed the image within the skin file. Use View Images to see the image. On the image window, you can see the numbers of the individual images. Use these numbers as parameter values. The size and type of image is shown on the top.

The next step is to edit all the parameter values in the skin file. Fill in the Description part with the appropriate values. The skin section contains the values that identifies the individual images. See the Skin Reference for a complete description of all parameters. See also Skin File Format for an example skin. Next use Validate Skin to make sure there are no errors. Run the Sokoban game and select your skin to see the result of your work, just make sure you saved the skin file in the path specified in the game options.