Aside from not being able to recover any ships you lose after disengaging (which encourages a sunk cost approach to the battle) (making the dead ships remain as salvage is great)...
I think the requirement to kill 40% or 100 DP (whichever is lower) means that clean disengage only really works in two scenarios:
- When you're badly outnumbered but have qualitative equality or superiority (so you can beat some of their ships, but would eventually get overwhelmed), and are close enough to the battle size limit that the enemy can't just swarm you under immediately.
- If you can't manage that much, sometimes it's possible to pilot a single supership and pick off enough enemies to meet the quota. Or at least get close enough that you can complete it by luring any remaining enemies to the bottom of the map, ganking them with a large allied deployment, then retreating before the enemy AI can send reinforcements after you.
In short, to clean disengage you have to be able to put up at least
some of a fight, while not being strong enough that you'd just fight and win. That's a pretty specific level of disadvantage.
Maybe there should be some benefit to partially meeting the quota, like a bigger head start if attempting the escape round? Or it could carry over between engagement rounds? Maybe escape scenario could be easier in some way in general (unsure how)?
I dunno about mechanics where the enemy fleet stops being aggressive if the player retreats after reaching the clean disengage threshold. It generates the desired gameplay in each case which is important, but there's still a dissonance where if you retreat the enemy stops trying to fight in order to preserve their remaining forces or whatever, but if you
don't retreat they all happily charge to their deaths until their fleet is almost completely annihilated.
But afterwards, when I want to actually retreat the ships to the boarder, it's a massacre. By now I order all my ships to stay as close to the lower border as possible, but still, the big slow ships take heavy losses the moment they turn around to flee. It's all but clean!
I generally put a Defend order on the slowest ship and retreat that. So everyone sticks together in a ball that's difficult for the enemy to take apart and scary for them to chase (or if it wasn't, my fleet would be dead already) and once the target ship retreats, everyone is near the border and should be able to make it off as well.