Games which are animation and graphics heavy, and which want to allow for heavy customisation and reuse, normally need to be able to manage collections of images which are not known at design time. You want something that lets you specify an abstract identifier and get back an appropriate version of the image for your current screen, potentially returning a whole series of images for animation purposes.

For our little game we put together a manager that can read metadata from resource.ini files in directories and use the metadata to pull in particular files for whatever roles are defined in the file. It can handle multiple resource directories and the like.

At some point I'm thinking we might refactor it to make it a little less rigid in the number of divisions involved, in a couple of cases I wound up just using "default" when describing a particular resource (particularly effects). Still, it does seem to work nicely.