If it is a 2D effect it's fairly well thought out and implemented. The shadow of the crater is oriented in the same direction as the shadow from the engine.

I guess we need some 3D infantry to hide in the crater to test! ;)

Cheers!

It almost sounds like some are confusing Bump Mapping and Parallax Mapping. Bump Mapping uses a shading texture to apply a shadow onto a flat 2D surface, whereas Parallax Mapping displaces the texture pixels of the surface according to a 3D-calculation, and thus gives the illusion of depth. This is a valid comparison. (though the right ball uses iso-surface alteration (actual surface alteration) rather than Parallax (surface texture pixel displacement), but should otherwise look somewhat similar.)

My guess on these game craters are that they are Parallaxed, as they are able to smoothly inherit the texture used by the ground without peculiar texture edge clippings, with an added invisible 3D hitbox to collide with. They also don't look that different from other parallaxed solutions found in games and engines such as Crysis, Stalker, Unreal Engine etc. Either that or an iso-surface displacement, but I'm uncertain of the spatial resolution of the crater versus that of the terrain, which probably is a bit more low-rez than the crater. One way to figure this out further is how precise it is in regards to collision. Haven't been able to experiment with craters as such myself, but how exact is it when colliding with prop tips or rolling over it with the wheels?

Some Parallaxed views from Stalker: Clear Sky and Crysis.
Stalker
More Stalker.
Crysis

You can also view them through buildings which causes a very weird floating effect. Any associated crater fire cannot be seen through buildings though. A bug I guess.

PPP