S.T.A.L.K.E.R. MMO a Possibility

While we haven't typically covered THQ and GSC's S.T.A.L.K.E.R.: Shadow of Chernobyl in the past, it's worth pointing out that the team may eventually develop a massively multiplayer version of the post-apocalyptic shooter hybrid, as pointed out in a new community Q&A on their forums.
2. Will there be S.T.A.L.K.E.R. Online?

We do not quite understand what you mean by "online". If it is the cooperative mode, then no, there will be none. Even at the time of development of the first part of the game we said that a cooperative mode is impossible, since Life Simulation would be different at each computer. Synchronizing it would be practically not doable. If you mean an MMOG, then we are seriously considering it.

Personally, I think the original would sell even more copies if they added a co-op component.