Just a bystander chiming in. Great job on this feature Meridian, such a cool addition.
I assume over ocean, everyone dies.
Not necessarily. Life rafts/life vests are a thing, even in today's commercial passenger planes.
B. If it doesn't spawn a mission, can we just simplify it that survivors come back home by public transport after certain amount of days?
Sounds like the simplest solution. Lose the craft and all equipment, but have a chance for survival/injury (based on whatever factors you think appropriate ie soldier health, armor, etc) and have them set to return to base in X days based on where they went down. Those that were seriously injured may require extra recovery time.
I agree with those have said that they wouldn't want to lose an entire squad of trained soldiers without even the opportunity for a fight. I think losing the craft and equipment (with the chance to lose a soldier or two ... I'd favor greater chance for survival/injury though) seems like an appropriate negative consequence so these HKs are a big concern, but not game-killing.
Does this actually spawn a mission or is it just a touch-and-go crash site?
A. If it spawns a mission, who will be the enemy?
And should the survivors spawn as xcom and fight as well?
Or should they spawn as civilians you need to save?
Or should they not spawn at all and just be recovered at the end? Or killed if you lose/abort.
If you're to go this route, it could immediately spawn an "escape" mission where the enemy is the race of the craft that shot you down. You have to get all the survivors to the exit and abort, whoever makes it survives and goes back to base. Lose the craft, only equipment recovered is what you had on you when escaping.
If you're worried about farming, make it so even if you kill all aliens on the map, you don't recover equipment/corpses on the ground, only what is on your soldiers. Justification is they still have to "escape" before another alien ship shows up. That said, I think losing a craft and potentially soldiers in the crash is a big enough loss you wouldn't want to use this as "farming."