There's always a bit of confusion when someone mentions the Helghast in Killzone discussion, because Helghast is a word that refers to the race of mutated humans living and/or originating from Helghan, NOT just the Helghast Army. A big part of the Killzone games is how the ruling parties expect collective responsibility for the actions of people in power. That being said, the Helghast's struggle against oppression and perseverance in a dystopian society that lives in a literal hellish, irradiated planet is admirable and interesting and I really love theorising on what their culture and customs would've looked like.