Basically to sum the tank game up...
Each server had... 4 teams? I think?
And when first joining a server, you can pick any team you want, but you can't switch for a while. I forget how exactly that worked.
And the servers were persistent. Meaning anything the players did to it would be permanent.
So for gameplay. You had your armor and fuel. Pretty sure if either of these went empty, you died.
Then the things you could do were... Move, scan, pick up items, and pick up blocks (not on top of the tank, but dragging/pushing it around as you moved). And normal shots of course.
All of those actions (except picking up items) costed fuel. You could turn into a boat to go across water but I forget the restrictions on that. Maybe it costs more fuel and you can't shoot? I don't remember. But it was mandatory so that you could drag and push blocks to make bridges. If you push a block into water, it becomes traversable. Where blocks on land were obstacles. There were natural unmovable obstacles as well.
Scanning would reveal hidden items and enemies behind cover I think.
Then the items you could pick up offered different types of shots. Like a more powerful one, or a longer range shot. As well as a very large scan, which would scan your whole screen. I think there was a refuel and repair item as well.
You leveled up but I don't quite remember if that did anything.
As for an objective... There wasn't really one. People would usually just try and control the center of the map, pushing all the blocks a certain way to make it impenetrable without dealing with tons of resistance. Was always neat to see a new team controlling it each day. The people who were usually on when I played were really good at taking it. We co-ordinated our attack very well.