You can see a little of the gameplay of it in the video I've posted. In the future you will be able to download my creations in .blend files and contribute with my projects.
Learn how to create a simple weapon in Blender and how to export it successfully onto a .md3 file in this tutorial. Learn how to replace a existing weapon on the game, this is the basis you need to create your own MD3 models. Probably is the basis for MD2 and MD5 too.
It works on Blender 2.49 (My version). With all the other existing exporters I've got size errors on the game and texture, so, I'm saving a lot of your time.