Coriolis has a stripped down mechanic that - I find - encourages dramatic story-telling over dice-rolling and chart-consulting.
At the same time, combat is quick and often deadly. So, the first rule is “avoid combat”.
When that fails, then as a GM I am happy to fudge the rules - or toss them over the side - for the sake of a good, dramatic story.
So - if the heroes want to disengage and avoid being exposed to one last attack, I would force them to describe how they’re going to do that. Where is everyone? Who can provide covering fire? What terrain can they use to their advantage, and so on. Be generous with it: if they’re in a warehouse and they describe diving into the gap between shipping containers, assume there are shipping containers for them to dive behind.
If the heroes describe a good scene, give yourself a Darkness Point and let them get away. This is especially important if they had no choice but to fight - eg: they were ambushed in a blind alley. If they describe a GREAT scene - eg: shooting up gas storage tanks to provide cover and a distraction, leaping from catwalk to catwalk near the ceiling of the warehouse, swinging on a cable like a Futuristic Arabian Spider Man - don’t take the Darkness Point: reward the creativity.
If the heroes don’t describe a good scene - if they simply say “we run away” and can’t embellish it - then give their opponents that final attack. But since they’ve forced you to do the heavy lifting, story wise, I’d narrate it instead of rolling dice. (If you must, roll some behind the screen, make a quick check of the charts, then tut and say “oh dear”.) Pick the PC with the best health and shoot them for a couple of points. Better yet, assign a mild critical hot that makes the escape more dramatic (“The security officer shoots Alia … and the bullet shatters her knee! She shrieks, stumbles and falls: who’s going back to help her?”) and that will require the group to seek medicurgical aid. Or you can make them lose an important piece of gear, a weapon, an NPC that you’re tired of running, etc. Spend a DP or two, depending on how much trouble you’ve just caused them.
I recently ran a session of “Feng Shui 2” for a couple of friends. It’s an RPG based on Hong Kong Action Movie tropes. Like the movies, there’s lots of fighting - melee and shootouts. The game is designed to encourage players to describe fights using action movie physics - so, heroes make impossible leaps, use their surroundings to subdue bad guys, etc. You never say, “I kick the guy with the axes” a you say “I leap in the air and fly feet first into Two-Axe Tom, knocking him down the stairs and through the window at the bottom.” (Note: The stairs and the window don’t exist until you describe them.)
We found the mechanic pretty clunky for an action movie, so on the fly I streamlined it to remove a lot of the chart-consulting I had to do. Also, I gave heroes a better chance of succeeding if their description impressed me.
The game immediately got a lot better.
As a result of that, I’m applying more that rule to other games - including Coriolis. Reward drama and storytelling and use the dice as a last resort.
I hope this helps!