Apparently so. Gamespot have done some hands-on impressions of STALKER, which I thought was established to be vaporware 8 years ago.
As we played through the level for the first time, we found ourselves
dying quite frequently, with the opposition cutting through us when we
were out in open positions. However, once we began to push the military
forces back, the stalker allies moved forward and became more
aggressive. Moving away from the area, we could see the A-Life
technology in action as a military helicopter flew in to replenish the
armed forces in the area. Shortly afterward, a THQ representative
demonstrated to us that with a little exploration, you can avoid the
fire fight altogether and find the underground opening that would have
been revealed if you had extracted the allied leader.
While S.T.A.L.K.E.R. is big on ideas, it currently looks a little dated
when compared to its next-generation contemporaries. The protracted
development period has clearly been used to polish the A-Life system
and branching storyline, and you have to scratch beneath the surface to
see these advancements. Thankfully, the game finally looks close to
completion, and THQ seems relatively certain that it will see the light
of day next year. While S.T.A.L.K.E.R. has more bad endings waiting for
its players than it does good, hopefully the game itself will have a
happy conclusion after all those years of work.
If it gets released, I am predicting a horrible buggy mess with ambitions far higher than the implentation. I'm also happy to be proved wrong in this case.