In real life, a scene lit by direct sunlight can be more than 1000 times brighter than an indoor room lit by a couple of standard lightbulbs. (and there is plenty of brightness variance in each scene)
Right now, games have to represent a range that big with only 256 levels of brightness.
The single player game already has a couple of places where it faked HDR. Before you emerge from the underground after the cavern filled with head crabs, you can see the opening, but it is just a white blur. The bright highlight fades away as you approach it.
This comment was edited on Feb 5, 04:34.