https://www.pcgamer.com/a-new-metro-exodus-trailer-shows-us-artyoms-nightmares/

A new Metro Exodus trailer that debuted during today's Inside Xbox livestream showcases some of the different environments and enemies that players will encounter as they traverse the ruined Russian landscape as the Spartan Artyom. More interestingly, it may also suggest that we haven't seen the last of the Dark Ones, the post-human mutants who figured prominently in the first two games. 

The Dark Ones were first presented as an enemy in Metro 2033, although it was eventually revealed that their powerful telepathic abilities were simply overwhelming the Metro survivors whenever they tried to communicate. That led to a spot of unhappy conflict resolution: No spoilers, but let's just say that in fine Russian post-apocalyptic style, the bad ending turned out to be the canon ending in Metro: Last Light. But they managed to persevere, and Last Light ultimate wrapped up on an ambiguous, but relatively upbeat, note.