

What if Ysanne Isard's plan is slightly changed...
Okay so for those that have absolutely 0 idea of what Im talking about let me start from scratch and give some context:
In this scenario, Ysanne Isard's plan is a bit different from her plan from the comics in which she essentially tricked Sate Pestage and the Imperial Ruling Council into blundering Brentaal 4, letting the New Republic gain a foothold in the Core Worlds and causing a political crisis which eventually led to both the Council and Pestage being removed from the picture allowing for Isard's rise to power. Yet there is one flaw, she let the New Republic gain a foothold in the Core Worlds. And she'd go on to let the New Republic get Coruscant itself in an overly complicated scheme to logistically cripple the New Republic through the Krytos Virus.
So what if her plan was changed a bit?
- Isard arranges for the Battle of Brentaal to be a failure, however, the epicenter of the Krytos Virus is not Coruscant but rather Brentaal IV. So now not only does she cause a political crisis for her political rivals that ends up paving the way for her ascension but she also is unleashing the Kyrtos Virus earlier than in the timeline.
- After seizing power and dealing with the Tribunal and later killing the Central Committee of Grand Moffs, Isard goes a step further and does the very same thing that the Galactic Republic did in the New Sith War which started the Republic's Dark Ages: disabling the hyperspace relays connecting the Core Worlds, Colonies, and parts of the Inner Rim to the rest of the galaxy
For those that still have no clue what Im talking about and what the Republic actually did in the New Sith War, let me show you what the Knight Errant Gazetter says:
>HISTORICAL BACKGROUND
>The dire conditions facing the Republic today require little amplification on my part. It is difficult to recall another time in history when so many factors have gone against those working to promote peace and good will.
>There is little need, for example, to describe our long years of war with the newly risen Sith Lords on the Outer Rim. The Grumani sector is one such nest of evil, but today's map of the galaxy shows many disparate areas under Sith control, like cancerous lesions. Alongside the Republic Navy, the Jedi Order sought to stem the tide by making stands on world after world, Republic-affiliated or not.
>But such efforts fell short, partially due to another factor: plague. If the Sith threat is the fire, the Candorian Plague proved a deadly and effective accelerant. Even the noblest defenders cannot stand long when their own bodies fail them. Systems under quarantine could not be defended -- and Sith Lords more interested in conquest than the well-beings of their own warriors took advantage. World after world fell to the Sith conquerors.
>Exceptional times call for exceptional measures. One such measure came when the Republic turned to Jedi for political leadership. Jedi Chancellors such as Your Grace have served to guide both the Republic and Order through many a storm.
>Another such measure was more extreme. controversial, and, sadly, probably necessary. Drawing a security cordon around the Core, the Colonies, and part of the Inner Rim, the Republic deactivated the hyperspace relays beyond. Both navigational and message relays were affected. Instantaneous communication with most of the Outer Rim ceased -- as did communication between those Rimworlds. No longer would the Sith Lords be able to easily exploit the existing Republic systems to speed their own conquests; hyperspace couriers came back into use across much of the galaxy.
>Perhaps more importantly, the action robbed the Sith of access to the constantly updated Republic database of hyperspace lanes. Many smaller vessels depend on hyperspace buoys to provide information as to their own location and other destinations; now, in many cases, Sith fliers are limited to the coordinates they bring with them. Scouting missions have revealed that some Sith Lords have constructed their own rudimentary hyperspace relay networks (in some cases, reverse-engineering or reactivating our own buoys), but thankfully, that has been a limited phenomenon. Most Sith genuinely do not know what lies beyond the stellar horizon -- and that has greatly added to the protection of the Republic. Our "firewall" is one of void and interstellar dust, using the vast distances between stars to slow the Sith spread.
>The Republic has thus managed to preserve a good deal of what our civilization has accomplished. The same, sadly, cannot be said for the locations outside the cordon, where great libraries and storehouses of ancient wisdom have been taken by Sith invaders, destroyed, or both. Technological advancement has, in large measure, stagnated in areas under Sith control. There is little commercial incentive for innovation; some Sith areas have no units of exchange at all, with all manufacturing done by slave labor or droids.
>There are corporations that continue to function under Sith rule; as will be seen, some Sith Lords permit firms to continue functioning in their space, provided they reap the rewards. The Republic has strongly encouraged all corporations with operations in Sith territory to withdraw behind the cordon, not just for the safety of their employees, but so that current Republic technology does not fall into Sith hands.
>So the Republic survives, though much smaller than it had once been. (The popular term "rump Republic" is distasteful, but does describe what remains.) The Jedi spend much of their year at the frontier, with only some of their time devoted to their traditional duties of keeping order on Republic worlds. Republic military forces battle valiantly to protect the frontiers from further encroachment -- and while engagements continue, the good news, if it can be called that, is that many of our opponents seem more interested in fighting each other than invading the Republic. Prolonging this period of disunity among the Sith is one of the goals of my efforts in general, and Operation Influx in particular.
So, with these conditions established: How much does the Galactic Civil War change?
Yes, this is also assuming that the Krytos Virus is ready earlier in the timeline for the sake of a more fun scenario.