The tank is now a real object with some degree of physics. It can be controlled with WASD, and the gun will aim at your mouse. The physics were done using JBullet, a Java port of the Bullet physics library (originally for C++). The mouse aim was done using what in professional circles is known as a giant heap of trig. I actually spent several hours trying to figure out why I wasn't getting the right values from the formula, only to realize that I had forgotten to convert from degrees to radians and back again, as LWJGL uses degrees but Java's Math class deals in radians. Earlier I had a ton of fun (the sarcasm is tangible) learning about quaternions and how to convert them to something recognizable to humans.
I realize now that it's hard to see the grass texture as a point of reference, but trust me, the tank is really moving. It's a lot clearer in-game, but the video rendering process made it blurry.