tarjan95: I have done lots of missions show me lots of vipers lots of sectoids lots of Mechs and never received more bodies. So exactly what do I need to bring on the mission to retrieve the bodies?
In the
standard version of the game corpses are just taken at the end of every mission.
In the
Long War mod, which you are possibly playing but haven't specified in this question, you will acquire corpses from a mission only of your team doesn't evac at the end, i.e. if the mission objective is to neutralize all aliens. This will happen on some random missions and during region liberation. Besides that you may sometimes have the option of acquiring some random corpses through resistance activities in the Ring facility.
Unfortunately, corpses cannot be picked up manually (like the bodies of your fallen soldiers can be), so even if you'd have enough time to haul some bodies to the evac point, the game won't let you do that. You'll just have to wait for an opportunity.
EDITED TO ADD: there are additional mods that patch corpse hauling into Long War, apparently. This is not the intended design and makes LW less challenging, but if you get really frustrated waiting for the right opportunity, you might give that a try.
