Having not long finished work on my post about ways to simplify space combat rules in my Rogue Trader FATE hack my thoughts started turning towards how initiative would would in the posited three zone space combat and how people would actually leave combat if they decided to flee rather than fight to the “death” (although obviously, the ship being “Taken Out” would not automatically mean death, more likely they have been boarded or are spiraling towards the surface of a planet, something more interesting like that).
The two ships (Lunatic Pandora and Venerus) commanded by the player characters would be about the size of a Hazeroth Class Privateer and a Dictator Class Cruiser respectively (as shown in the image above) and, despite not being as vast as the hugest of the ships commanded by the Imperium of Man, they are still fairly massive vessels (coming in at a length of 1600m and 3500m).
This was fairly straight forward, the ships would make rolls using their Engine Skill or (if a PC or named-NPC was crewing that station) their Drive(spacecraft) Skill and then would take their moves in turns from highest to low, these could be modified as usual using Aspects or (if appropriate) Stunts.
For example: someone might have an Aspect of Advanced Scanners and spend a fate point to add +2 to their initiative because they’ve been able to pick up the other vessels and react sooner.
Escaping from Space Combat
The most likely way of fleeing the area completely in a WH40K space combat (IMO) would be for the ship to activate its warp engines and and drop into the Immaterium; with this in mind I decided that any ship that did not have an enemy vessel in it’s zone could make a Fair (+2) Engine roll (or, if crewed by a player or named-NPC the Navigator could make the same difficulty Will roll) to enter the warp and leave the combat.