Aliens: Dark Descent

There are 3 survivors that you can rescue in mission 1 - only 1 is an objective so the other 2 you need to find. One is in the sheriffs office, in prison (building above the bar). The other survivor is on the upper level, bottom left corner in a room with the doors welded shut. The last survivor is the vet you rescue at the end (no spoilers!)

On mission 2, there are 3 survivors as well. Two you can rescue from the cultists (secondary objective) and another one on the second level (in a room to the right and down of the map room).

If you have rescued 5 (or 6) the achievement will pop as you exit/complete level 2.

Good luck!!