As far as I know there is no mandatory DRM on Steam either, so if a publisher wants to they can just make their game be portable and not require Steam to even be installed. Pretty sure all the re-releases that use DOSBox or ScummVM are like this, for example.
It seems like a pretty good story to tell those evil westerners: Actually Russia is crazy enough to start a nuclear exchange because of wacky religious bullshit, so better appease them!