The STALKER series was one that was fondly looked upon by many gamers, myself included, and to find that the development for the sequel is not only ceased but that the very development team working on it in GSC is no more just blows my mind.
What we have in its place is Survarium, an MMOFPS.
"Survarium is a free2play MMOFPS game set in the near future. The game focuses on a mass-scale ecological catastrophe on Earth, the reasons behind vaguely known.
Impassable woods advance onto cities from every side, maddened animals and birds attack industrial complexes, military structures, warehouses and power plants. Strange plants and mushrooms grow through concrete and steel. Scientists all over the world haplessly try to cope with the anomaly sprawling across the Earth with terrifying speed. Countries collapse, anarchy spreads throughout the world. Now force dictates who to survive.
The game is developed with a new proprietary Vostok Engine technology and is planned for release on PC at the end of 2013."
Here is some more confirmation straight from the horse's mouth.