This will be a Star Wars Saga Edition game. We'll be starting at 1st level, but using some notable houserules for character creation - notably, every character will be a Force-sensitive apprentice from a Force tradition other than the Jedi.
I like to leave a lot of wiggle room based on what the party wants and pursues, but the game will begin with you all being trained as Sith. We'll discuss as a group whether you think your arc should be about going dark and drinking the Kool-aid, or trying to hold on to the Light and escaping. Past that, we'll just have to see how things go.
The game is set some time after Episode III. It will begin in an isolated Sith academy on Morabund, and the party may not leave the academy for several levels of advancement - some of it will depend on your choices, but in general you won't be allowed to leave until your Master deems you ready. So expect a somewhat education-oriented, roleplay-heavy game to begin with, almost a school atmosphere.
We'll primarily be using the new canon, but obviously a lot of the Force traditions and other details will be drawn from Legends. I may also diverge from either canon just to keep you on your toes a bit - your characters will be strangers in a strange world, not sure what to expect or believe, and I want to preserve a bit of that for you, the players.
In particular, your Sith masters will have a lot to say about the Dark Side of the Force; some of it is undoubtedly lies, but it won't always be the parts you expect. And they might not always be right about stuff. If your only source for a fact about how the Force works is in-character, it might not be true - but don't assume it's false just because it contradicts how the Force works in other Star Wars stories.
Despite me starting the game with some notable houserules, in general I will be sticking to established mechanics even when they don't always make sense - I like to give the game the benefit of the doubt. That said, if some builds, abilities, or whatnot end up so good as to be overpowering or so weak as to be disappointing, I may not act quickly, but I will eventually make calls, ask for (or allow) rebuilds, or whatever.
I tend to give a lot of bonus experience for roleplaying, completing missions, etc., so expect advancement to be a little faster than normal.
I know this could get fuzzy given the Dark-tinted nature of the setting, so I'm going to restate something I know you all already know: Your characters should all be team players and work with each other, even if that doesn't make perfect sense in-universe. I expect you to go out of your way to come up with reasons that your characters would work well together, or to ignore reasons that your characters wouldn't. This isn't to say you all need to like each other, or that you can never disagree or argue - just that at the end of the argument, you need to end up on the same page.
To be clear, I don't care if you all turn Dark and become hardcore bad guys, I don't care if half of you are light and half of you are dark, everything is fine as long as you're all able to stick together.
If you absolutely must do something sneaky and conniving IC, you should get the whole group's approval first OOC. Just trust everyone to roleplay their lack of knowledge.
This is a harsh setting, and I will not shy away from killing characters if that would make sense. That said, Force Points provide a nice buffer for staying alive, and while your masters want to weed out the weak from the strong, they are going to try to help you survive long enough to be useful. I'm not going to try to kill you, I'm just not going to run from it.