The achievement states: Complete mission 4 without one preventable Marine death on Heroic or harder…
Can someone clarify this? Do we have to save marines that are under attack? Or do we just have to keep the marines that later join our party alive ? If a marine dies, and you reload to a checkpoint (or die), can you still get this achievement – or do you have to start the complete mission over?
Best Answer
Try the mission on easy, you should be able to save everyone. Except those that die because they are scripted to.
Those scripted to die will always do so under the excact same circumstances, even on higher difficulty.
Also, here's a video guide: Link