To be honest I am not entirely sure what you are asking. If I understand you correctly, then I think what you describe often covers mutiple genres. Some titles of this nature could be described as neo-noirist works, but the genre also covers the likes Chinatown which is certainly not what your talking about. Terms like Post-50's B-Movie or Neo-noirist Science Fiction would describe Sky Captain and Dark City respectively, but I cant think of a genre term more specfic than science fiction which accurately encompasses both.