There are a number of places I’ve found where choices have meaningful impact to the Jedi Knight storyline.
Storyline Impact
[spoiler]There’s a mid-planet boss fight, for example, where you’re confronting a gangster and his group of thugs. The option is presented to do the Jedi mind trick on them. It doesn’t work on the boss (he shakes it off), but the adds all decide to “rethink their lives” or somesuch and go away. A very difficult fight with the adds becomes a cakewalk with just the boss.
There are a couple other storylines where you can use the Jedi mind trick to avoid combat entirely (or not use it and end up in combat). There’s one such small side quest of that sort on Coruscant. I chose the Jedi mind trick there thinking “this will never work” and was surprised to find that it resolved the quest entirely and immediately.
There’s another place on Nar Shaddaa where your allies are ready to flee. You can let them go, persuade them to stay, or Jedi mind trick them to stay. I used the Jedi mind trick. They stayed. Later on, one of the characters (after showing up after the end of a boss fight as late reinforcements arriving) complained about me messing with his mind, telling me he didn’t like something I was doing, but knew better than to try and stop me or refuse to help, since I’d clearly just mess with his head and force him to do it anyway.
I’m not sure what would have happened if I had taken the other paths. I assume that they could have been persuaded to stay. If I had let them go entirely, maybe they would have had second thoughts and decided to come back and help. Who knows. I do know that the dialogue element involving the Jedi mind trick would have been different.
There are also various places where you have off-screen assistance, and you choose whether they should keep fighting (as a distraction) or not. The subsequent interactions reflect the outcome of your decisions in the storyline tree; sometimes the off-screen assisting force is wiped out, for example, or if you don’t send them there are (apparently) additional spawns in your storyline area. You basically choose whether to spend the lives of your allies to make your own mission easier, or not. Some such choices are LS-DS scored; some are not.
Another one I found involves a late-game discovery of a romance between two other characters present in the storyline. If you’re romancing Kira (or presumably the male companion romance option if female) and the romanced companion is present, their reaction to how you deal with that romance (exposing it to the Jedi Council or not) is shown on screen. There’s an option to say something like “I don’t agree with the Council’s stance on romantic relationships” or something, and Kira snarks, “Understatement.”
And the tone of how that particular conversation goes is itself, apparently, somewhat related to at least one of your earlier interactions with one of the romatically-involved Jedi (you have prior interaction with both, one of which had the potential to be quite contentious).
There are a number of LS-DS choices by the Jedi Knight that apparently have impact (sometimes off-screen and seen only in post-quest followup emails). Kill this person versus spare this person. Expose this versus agree to cover this up.
On Voss, there’s a culminating decision at the end of the planetary quest line that can go several ways. I chose the obvious goody-goody choice, but I’m curious what would have happened had I not, particularly since some of the verbiage for the bonus quest for Voss appears to imply a return to the planet to deal with fallout from having made the goody-goody choice. Maybe the interactions of the bonus quest are slightly different if you choose the other path; I’m curious to know.
However, this all being said, there were earlier points on Voss where you’re trying to be diplomatic and improve the Republic’s standing with the Voss and make the Sith look bad, and pretty much anything you say at any conversation choice (I always took what appeared to be the most diplomatic option) appears to be taken and twisted by the Sith ambassador, and the Voss don’t seem happy with some of what you say either. Presumably there was no good way to be successfully diplomatic there, but it was irritating to try and have it come to nothing.[/spoiler]
You can’t get too far into the tall grass away from the main storyline; this is a computer game, after all, and there are practical limitations to how large the decision tree could be given that voice actors are involved. But there appear to be various paths toward the end goals shared by players, and various decisions that can have impacts later on.
You’re on rails, it’s true, and there are stations along the way that everyone has to check into. But you can get yourself diverted onto various tracks along the way on your way to those stations.
I sort of think of it like driving between two cities. I’m going to get there eventually. But I might stop and eat on the way (or not). I might speed and get pulled over (or not). I might text while driving and have a wreck (or not). I might pull over and help a guy with a flat tire (or not) and doing so may incline him to help me out down the road (or not). But the convention of the game is to go to the destination city eventually. There’s no going somewhere else as a destination instead.
