Aliens: Dark Descent

I thought I'd just add to the collection here that you can get this early on and relatively quickly, in a secondary save so as not to throw off anything from your main.

Just start a new game, skipping the prologue, and play through the motions at the start of Dead Hills until the earliest opportunity to extract, which is once you come down the lift and exit the warehouse.

DO NOT free and extract the guy in the cell at the sheriff's office.

Again, follow the motions back at HQ until you can redeploy, deleting all but one member of the squad and skipping over the warning message, then deploy to the spot outside the bar (it defaulted to this spot for me anyways) and send your lone wolf marine to free the con and extract him.

If you feel safer, you can weld the door of the sheriff's office shut, but the armored car does a pretty good job of keeping the street clear on Story.

The achievement pops as soon as you hit the extract survivor prompt. Job done.

The clue is in the name really, easiest way to ensure your squad is mostly dead would be to use the “barrage” ability on your troops (send one of them away to deploy a motion scanner so they aren’t hit).

Before doing this I’d get up to a point just before turning in an objective.

Maim your squad and then turn in the objective (reload your last save if you want your troops back)

You’ll know the objective was turned in if you’re awarded XP.

This achievement popped for me upon finishing the last level of the game, so no need to do anything specific if you're willing to wait.

For more specific details on the level:

This achievement popped for me upon finishing the last level of the game, so no need to do anything specific if you're willing to wait.

For more specific details on the level: