I generally like how you kept the core races etc. I am wondering though .. Why you chose to have certain tech be required to make various cap ships? I've noticed this trend in nearly every mod. I feel like it's left over from old RTS thinking. With CORE sins all the cap ships are always Valuable and all have their uses however, in mods like this it feels like the you're stuck with the Early cap ships and then when the good stuff comes down later in the tech tree you've got these useless caps you spent time leveling and fighting with etc.
The problem is that 4 of the Empire's capitalships, the Imperial-I, Imperial-II, Tector and Interdictor Star Destroyers, are bigger, have better stats and are more expensive than the default capitalships. By default in Sins your first capitalship is free, so if you could build these capitalships right away you could get an Imperial II Star Destroyer than costs something like 4500 credits, while the Vanilla races would get their standard 3000 credit capitalships that are overall somewhat weaker. So any capitalships that is substantially stronger than vanilla capitalships will need to have research to prevent the player from getting these capitalships for free at the start of the game.
The Venator Star Destroyer, AKA the one from Episode 3, has research because it is more commonly associated with the Republic, not the Empire, and I wanted to reflect that it was not necessarily common by making it harder to get.
Also I've had several people tell me that those Victory Star Destroyers are quite useful. The Victory-I is what you should probably always get first anyway, because while your Sentinel Landing Craft colony frigates are very cheap, they are consumed when they colonize a planet, so having a colony capitalship is more useful to the Empire. If you keep it alive later in the game its siege abilities help you clear out enemy planets much faster. The Victory-II on the other hand can be useful for crippling enemy ships firepower with Disruptive Ion Bolts and giving antimatter to your other Star Destroyers with redoubled efforts.
I will say that the Empire will suffer the most from this problem. The Rebels will have 4 capitalships to pick from without research, and the New Republic will have at least 3.
And a totally separate question where did that 4X add on come from?
It is actually the base for the mod, not an addon, since Interregnum needs it to run. Long story short, many years ago I was one of the devs of the Star Wars Requiem mod. However, that mod's philosophy was to stay very close to Vanilla mechanics, and as I got better at modding I got a bit bored with those. So I switched to making the Enhanced 4X Mod (just a vanilla races enhancement mod) in an attempt to make Sins play the way I wanted it to play, as well as adding new features that would be needed when I would start working on Star Wars again, such as the Hero Units. Once E4X got to a state I was happy with about one year ago I started making my own Star Wars mod, Interregnum, from scratch. This is the result at this time.
Also I am not the biggest Star Wars fan.. as you can tell from my Avatar lol however that Republic Star Destroyer you posted a pic of a few paragraphs above looks amazing. Did you do that whole design and concept from scratch yourself?
It's a model of the Nebula Star Destroyer from the Star Wars expanded universe, or Star Wars Legends universe as they're calling it now since Episode VII has destroyed it. Basically its a warship from the Star Wars novels built by the New Republic, I.e. the Rebel Alliance after they captured Coruscant from the Empire a few years after Episode VI. Apparently this picture is from one of the Star Wars sourcebooks.
Sadly this model is much too nice to fit in the Sins engine, but this ship will appear as one of the New Republic faction's best capitalships. It is certainly one of my favorite designs of theirs.
Since you're not a big Star Wars fan, I will say that another way of looking at the factions in (or will be in) this mod is as follows.
Galactic Empire - The Empire based as it was in the original trilogy.
Warlords - Empire based on the various Warlords/Imperial Remnant from the Expanded Universe.
Rebel Alliance - Rebels as they were in the original trilogy.
New Republic - The good guys after they established a legitimate government in the Expanded Universe.
Also to be perfectly honest, I'm not exactly sure what your avatar is.