Have I missed a rule somewhere in the force power section about range and force powers? More than a few of the movies and tv shows show use of force powers through holograms sometimes at galactic distances.

Generally, such things are the bailiwick of "epic," a.k.a. narrative abilities. The only instances I'm familiar with are Vader Force-choking someone in Empire, and Mother Talzin using her VooDooku to affect the Count from across the galaxy in Clone Wars. Other than that, there really isn't much.

The Vader scene is easy; he's a very powerful Force user, all he needed was the holo-call to get a lock on his target, and he had the pips necessary to boost his Bind up to Extreme range. Gets everywhere on his ship, so he can choke his (former) Admiral out. Talzin's trick with the VooDooku was a bit different, so chalk that up to epic Nightsister mojo and call it good.

If there are other instances (no spoilers, for TLJ, please!), I can try to help. But in general, no, there's nothing you missed. The longest distance achievable so far is With Battle Meditation and Farsight, which can get effects out to Planetary Extreme range with enough pips, but that's generally within the same solar system, at best.

Sidious force chokes Dooku to make a point from Corescant to Serenno (I assume), in the last season of clone wars in “the lost one” episode. It’s canon too.

Voodooku I love it.

Ah, I'd forgotten that one. Still, let's chalk that up to Sidious being Sidious. If anyone had internalized the grand, " size distance matters not," truth that Yoda spoke of, we can assume it's Palpatine. And since it's not something that happens more than once, we can assume it's, at best, a narrative use of a Destiny Point on behalf of the big boss of the entire campaign. Not something that should be repeatable on anything remotely like a regular frequency.

EDIT: If you want something more solid, I'd just create an NPC ability:

Distance Matters Not: Once per session, the character can spend a Destiny Point to allow their Force powers to work over any range. They must still have a method to target the power, such as an live hologram of the target person or location, if they are beyond normal visual range.

You could give it to the three major Force users: Palpatine, Yoda (who clearly watches Luke with Farsight from across the galaxy), and Talzin, and then you're golden.

I can think of another, Barris Offee chokes some person to death in a prison cell in front of Ashoka Tano, while not being present in the cell and while not having visual sight (at least I can’t imagine she had access to prison holograms unless she was working for Palpatine at that point).

You know, I'd always assumed that Barris was in the prison at the same time on some trumped-up reason, just so she could do that. Since we don't actually know where Barris was at that point, we can't say she wasn't standing on the other side of the back wall of that prison cell. So, while it could be an instance, we can't know that it is.

[Spoilers for TLJ] We also have three scenes in TLJ, one where one individual throws around another from 15 or so kilometers away via hologram, another where the same individual connects two minds across the length of the galaxy and the third where a seperate individual projects an illusion/battle meditation across the galaxy.

Couldn’t you make a control upgrade to Move, Bind, etc: “Once per session, force user may extend the range of force power to include any target that can be accurately perceived” (cost appropriate to your group)

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