As of now just finished the base-game story mode. Very entertaining game if you liked those tower-defense and RTS games where an AI-controlled opponent operates in swarms that start to follow fluid dynamics you aught to enjoy this. Found I could bull my way through the campaign on normal mostly using officers, medical pods, and whatever assortment of shotguns, snipers, and miniguns seemed apropos to make pushes. Pretty sure the skill floor for higher difficulties might require more planning though.
