OpenArena is a 3d game creation engine. It is a rendering system that can be used for more than just games but it is targeted at games. The basic use being create some game media textures models maps and config files for physics and rules.
You can 'wear' any clothes on the internet 'virtually' on your body (image). And this application stores the URL where you can buy the clothes, you can share your information like your good looking shot or your ratingson the clothe over internet.