In ES2, blockade is just a way to pause fleets for a moment while they are en route to other star systems; if you only have one fleet blockading, you can only engage one of the many fleets that may be passing by at the same time. The rest are free to pass by the next turn. But what if there was a tech to make it possible to stall all of the fleets that enter the system, trapping them there in a way similar to the first ES?


It wouldn't have to be an ability available from the start, but could be integrated into the tech tree: an interdiction module. Such a thing has plenty of grounding in science fiction battles already, as a way to deny access to hyperspace or other means of FTL travel to fleets, and keep them from escaping. Adding an interdiction module to a fleet could make it possible for even just one fleet to hold several other fleets in check, keeping them from passing on to other locations.


There could even be a capability (either inherent or via upgrade) to expand the area of effect, and slow the travel of ships passing near a system that a fleet with an interdiction module is blockading at, making it difficult to even bypass the system outside of normal lanes.


While ES2 has numerous offensive modules, there is a lack of capability for a purely defensive strategy. If you want to hold the line, rather than go on the offensive, you're mostly out of luck. Adding a module like this would add another dimension to play.