What kinda wonders me, it looks like for Underworld they used the same Graphic engine. Okay, Lara has some more moves and animations, but basically, if you look at the Level Designer from FarCry 2, almost every talented designer can make great Levels with the Editor within a couple of hours or less.
Now imagine a Team of professional level designers and you have a new TR game ready in a month.
Using a existing Graphic engine, add some new animations and new levels and you have a new game.
I have a suspiscion that this game is just a fast production to make money.