I work in that project many months ago, but it has not been released until few weeks ago. It was a nice experience, making turrets and chain-wheels. Every tank has three part, wheels, body and turret. In game tanks are customized by the user, so all the pieces must fit together with all tanks. Textures are greyscale and there's only a diffuse and a specular. The color goes by vertex color and the cammo its an overlay texture added by the shader. The ones in the picture are my ones.
I have also worked in the environment of the market where the user customize his own tank. Its one of the fisrt full environments I do, and I did it together with Javi, my old partner, who was more experienced than me. In the beggining the garage was full of objects and chains with hooks hanging from the ceiling, but continuous feedbacks removed almost everything until we had a clean more o less empty space.