An entire new arena to fight against - ground vehicles.
They hug and move along the terrain (hovering above the ground). They turn around when they hit an obstacle.
In the early 'civilian' areas, they will be little ground transport vehicles like those shown here...but later....ahh...later....
Later they will be moving weapons platforms, laser cannons, etc.
And then - to make matters worse - picture them hugging the top of tunnels!!!
Ahh yes.....getting excited!!!