I'm not going to give any details yet, but I will explain what's going on in the video. You are given a (currently untextured) 3D model of a tank, which you can fly around and look at. You can also control the turret rotation and gun elevation/depression using the arrow keys. It's not much, I know; the important thing here is that it has 3D graphics -- something I've never personally experimented much with until now.
Like Shipyard, the game runs in Java. However, rather than using Java's built-in graphics API the way Shipyard does, this demo uses LWJGL. The code is, at this point, cobbled together from various tutorials, but as I get more used to OpenGL, I find myself relying on them less and less. The next step will probably be to add some sort of simple game world and make the tank actually playable. I already have various plans for the finished product, but I'm going to keep those to myself until I'm certain I can actually make them happen.