The creatures are the Weeping Bats (aka miners) from Silent Hill: Downpour which can be downloaded from the workshop. The fem. Ark Mars models were likely downloaded from somewhere on line. As for the gore it looks as if to be the l4d 2 gibs (also is available for the workshop).
those things seem to act like free willed darklings... the only thing missing is teeth, lips, 3 fingers(excluding the thumb), dark skin, glowing eyes, and random fashion senses... mainly gangster outfits XD I'm a bit of a The Darkness fan. no I am not referring to the band "The Darkness", I am however referring to the comics.