Tachyon's "branching" was rather simplified... so simplified in fact that the war between the Bora and GalSpan is won by one simple action: the player choosing which side to fight for when the Bora were ordered to move out of the Hub. The campaigns might have been tied together better if the main plot-line behind them hadn't changed... preferably with the Bora winning since its riper for sequels.
Also, the fact that there was no possible way to defect to the either side after that mission closes a lot of potential arcs that would span across both sides. Jake was always a heralded as a contract pilot, never commissioned, which means he had the potential to work on both sides during the whole conflict... so long as he was careful to not let either GalSpan or the Bora know about the ordeal (Like showing up to a GalSpan mission in a Bora Warhammer. Not a good idea when your working with the commissioned pilots or flying freely through GalSpan's territories.)
In FreeSpace, you play the role as a pilot. Not an officer. You don't make the decisions on which mission to take, you do as your told or try to retire to the private sector.
might've been able to do like what was done in Rainbow Six, where you were able to change the mission plan right before entering it, or accept the default mission plan and get cracking.
z64555: Ey! I actually love enemies trying to evade my shots, that's one of the reasons I still play Unreal 1 today!
WoD's take on it just feels... floppy (for the lack of a better word) when I play.
It probably has to do with the way the AI reacts... I don't think they have any delay in their routines to emulate human behavior when it comes to things changing in real-time (which I think is like 100 ~ 500ms). Even in FS and FS2 I couldn't believe how smoothly the Shivans were responding to the direction of my fighter as I was right on their tails.