Jink Engine

[SilverWarior]

Games such as space engineers and star-made must have a technique for this but it's hard to find any information - I'm guessing an algorithm that constructs geometry from 'holes' in the voxel chunks that's used for more optimal culling or portal generation.

I guess you probably missed it but Ken Software actually decided to provide access to full source code of Space Engineers
http://blog.marekrosa.org/2015/05/sp...access_40.html
http://www.spaceengineersgame.com/mo...urce-code.html

EDIT : oh yes sorry! I read up on star citizen how they had external forces applied to objects inside ships and they were raving about what an achievement this was.

All to increase sales. They weren't the first to use such approach as I have seen it in an older game whose name I can't remember.
What is strange to me is that such feature is pretty rarely used in space sims.

I mean stop me if I'm wrong but in my setup, I just take the force vector from my ship and apply it to objects 'inside' right? I mean that's around 20 seconds of work - not seeing why they were jumping up and down about it.

Yes that is if you are using your own physics engine. But if you are using some other physics engine which does not support multi-world physics simulation like older versions of PhysX for instance then implementing of something like this can be quite difficult.
Also you need to consider the fact that inside your ship you would probably want to have much higher precision of physics simulation than for your ship.

Or a blasted hole in the side of the ship could generate forces to 'suck' objects through the hole portal into outer-space - which would be very cool - surely some game already does that by now.

In Space Engineers blasting hole or opening a door of a pressurized compartment will generate force that will push you outward if you are close but nothing dramatic. Not sure if it affects other items (don't play it a lot lately).
About a year ago I have seen a video of a tech demonstration for a game where opening and airlock could literally such things (characters, furniture, etc) out of it. Unfortunately I don't remember its name. I'm really interested to know about how much progress has been done on it since then.