I think there is a Railgun immunity.
Part of the fun of Sid Meier's Alpha Centauri was that every single technology had some sort of progression based on the previous technologies (following the tradition of the Civ II tech tree I think) and meaningful name attached to it. It's a completely unfair thing to apply to a game like AI War, which thrives on dozens and dozens of unique ships and the freedom to make up ship abilities on the spot and have them out the door and in players' (and AIs') sweaty little hands on a near-weekly basis.
Also, AI War takes place after humanity's tech has reached it's peak, such that it is able to strike back, and so it isn't really necessary to speak to the context of individual technologies, and is even appropriate to obscure them, since they've advanced so far that one could probably take them for granted.
Still, it's fun to make up stuff like this.
So: Railgun Immunity. What should we call it? "Instantaneous Predictive Mass Dispersal" is my proposal.