Helldivers 2 showing real signs at being Sony's 2nd biggest game ever, only behind Fate Grand Order which is a mobile game. Arrowhead's price is probably doubling/trippling on a daily basis. The positive word of mouth for this game is out of control.
Imagine telling someone before 2020 that Helldivers's sequel would have 100x the concurrent players of Rocksteady's next big thing.
Just based on what I'm seeing... Humour, animations, explosions, lighting, core mechanics/controls are the game's standouts. What it needs is enemy and mission variety from what I can tell.