Freespace: Silent Threat https://www.gog.com/forum/freespace_series/freespace_insane_difficulty_has_anyone_finished_it/post15
This was the vanilla GOG version. I managed to finish this in Insane difficulty level. Some of the missions were quite hard, especially now remembering the Exodus mission (4th last mission where the main problem is you'd have to be in several places at the same time, and you have slow Hercules wingmen so they are not that much help there either. :)
The last mission "Secrets Revealed" wasn't really that hard at all as long as you use a couple of tricks. Some walkthroughs suggested it is the hardest mission in all Freespace, but I disagree. E.g. the last mission in the main campaign was much harder to me, especially because there was in practice a time limit, and you didn't get to choose your ships and weapons freely in the beginning of the mission, and last but not least, you had no shields!
What I liked about Freespace:
+ In most missions you get to select both your and your wingmen's fighters and weapons quite freely. I liked this very much, allowing you to try completely different approaches to the harder missions, e.g. slow but durable bomber with an autoturret vs. a fast and nimble fighter.
+ Missions were pretty varied, and some of them felt like puzzles you just needed to figure out. e.g. how to use your wingmen to your advantage efficiently, how to even avoid fighting etc. Many missions allowed quite unconventional approaches to them, probably ones that the game designers hadn't even thought of.
What I didn't like about Freespace:
- I disliked the early missions in the main campaign where you had no shield technology, as any shot to your hull would bring you closer to failing the mission. I disliked missions in Tie Fighter too where you were flying some fighter with no shields (Tie Fighter/Bomber etc.).
- In the Insane difficulty level, sometimes the dogfights with enemies became pretty much impossible. Sometimes engaging even one enemy fighter turned out to be a suicide to you for some reason (while at other times you'd be doing just fine against even several enemies), I can't quite put my finger on it why that was. Sometimes the enemy fighters just were all over you, no matter what you'd do you'd be taking constant damage from them and be dead in a matter of seconds.
In those cases the game became a bit frustrating exercise of "how to fool the game so that you don't have to fight the enemies". This made the game a bit less interesting as a space combat sim, a bit like a first-person shooter where you'd just try to avoid any encounters (that's not a FPS, but a stealth game!). Also it seemed in many missions there would be an endless supply of enemy fighters, making it that more futile trying to fight them.
For this reason, I personally felt that e.g. the dogfighting in Wing Commander: Prophecy Gold was more satisfying than in Freespace overall. At least in WC:P you got to fight the enemies, instead of figuring out how to avoid them and fight them as little as possible.
- The same applies even more to fighting big enemy ships. Fighting them in the Insane level was usually quite a frustrating experience. Their autoturrets and cannons were constantly firing at you so that usually it became pretty much impossible to wait for e.g. bombs or missiles to get a lock, and with guns you'd get only some short potshots here and there at the enemy, without getting severe damage to you.
Destroying the ship's weapon subsystem was supposed to help somewhat (making autoturrets less active?), but to me it seemed to have only minor effect. The other option would be to destroy the autoturrets/cannons/missile launchers themselves... but they seemed oddly durable. You'd have to shoot at them quite long in order to destroy them, so usually this was not a viable option either.
Also, I felt those big ass bombs against ships were mostly useless. If you tried to launch them far away, the autoturrets would destroy them easily. If you launched them next to the enemy ship, you'd take damage from the blast as well. For that reason, I never saw a reason trying to use them myself.
So in the end, destroying enemy motherships became an exercise finding a safe cranny somewhere in the ship's hull where you could avoid both autoturrets and enemy fighters, and then keep shooting the ship's hull until it is destroyed. Trying to destroy them some other way seemed usually pretty fruitless, you'd have six enemy fighters on your tail all the time, constant fire at you from autoturrets and cannons, and missile launchers sending missiles at you every 3 seconds or so. Just stupid.
There are still individual extra missions in the Freespace mission simulator, are they worth playing? I tried a couple of them already.