1. Will a Singleplayer SDK be released?So there you have it, two bad news (no SDK, no coop) and one good news (considering MMOfying S.T.A.L.K.E.R.).
We really did plan to release an SDK for the singleplayer part of the game, however right now the whole team is busy with development of "Clear Sky" and cannot devote enough time to the SDK. We cannot release our tools the way they currently are, since they are meant for internal use and would be extremely complicated for other people. So, the answer is - certainly not at this time, but maybe sometime later.
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.
Community Q&A 2007-11 Answers