Role-playing specialist Obsidian is making a free-to-play online tank game called Armored Warfare, a bizarre fit but one that pays the bills. I played it at Gamescom and it was entertaining, and now a video of the demo I played has emerged from PAX.
It's long and narrated, and very excitedly, but it explains what's going on.
What you don't really see are the deeper base mechanics and the relationships you'll forge with dealers as you play - the stuff that happens between the tank battles. These are the RPG underlayers that make the whole thing feel a bit more Obsidian.
You assign crews to tanks, for instance, and they can level up and gain abilities and skills, and in turn make your tanks more capable. And the tanks themselves can be fitted out with better equipment too.