The January issue of PLAY magazine will feature a first look at Tomb Raider Underworld, which is said to take place in after the events of Tomb Raider Legend.
According to the article, quotes heavily over at The Tomb Raider Chronicles, the game's emphasis is on "bringing Lara's world to life, a lush, vast, interactive world that reacts and remembers. It's pure woman versus the wild."
For instance, in a level in Southern Mexico, Lara leaves footprints behind in the mud, which are eventually washed away by the rain. The bodies of those she kill, though, will stay as will debris from her destructive path.