The Thing: Remastered

This wasn't as hard as I thought it would be. From what I can tell, "Maximum Fear Level" is when the icon above the NPC's head turns RED and they crouch down in panic and no longer take orders. I also read that they can kill themselves as well at the max fear level, but I never personally saw that happen so it was not an issue. NPCs turning into Thing monsters also does not count against you, it is only the NPC human squad members that count. There are many points in the game too where your entire squad just gets wiped out or does not proceed with you to the next level, and this did not affect the achievement either. You just have to make sure they never lose it on you and freak out completely. Simple as. I played the entire game on EASY difficulty, which I am sure helped make this easier to achieve.

The best way to do it I think is to use all the save slots and save as frequent and often as possible, and if you see this happen to an NPC then just load your game. I only had it happen twice, once in the stealth lab level, the first NPC medic that you find went nuts and ran off in the cell room. He saw a bunch of Thing monster spiders and would not respond to my orders anymore. The other instance was near the end of the game when an NPC engineer needs to hack a terminal in a blood-soaked room with a corpse hanging from a rope. This caused him to panic and I had to shoot him up with adrenaline to keep him from losing it and remain sane during that particular section. Remember: if anything like this happens, just reload a save and you'll be good to go.

Another super helpful strategy that worked wonders for me was to have your squad of NPCs "Hold Position" in safe areas. Safe areas are areas that don't have any enemies or dead bodies/gore in the environment. The game is simple enough for the most part soloing through it, so on EASY you don't really need your squad to follow you all the time, and when you need an engineer for a door or panel just backtrack to where you had them hold and bring him to the spot after you clear out the threats. Backtracking this way also keeps your medics alive too so they can heal you each time you return, it was just an extremely useful strategy for me throughout the game.

Lastly some quick things to note and stress: You can see how they are doing in the squad menu, their face starts to look around nervously and then shake rapidly the closer they are to going nuts. I found it helpful to check on them every now and again. Giving them weapons and ammo and healing them with health packs seems to make them pretty happy, so always try to do that when possible. Adrenaline shots will also keep them calm in "stressful" sections of the game, but I found it easier to just have them wait somewhere safe as mentioned before while I cleared the rooms out, and then backtracked to get the squad after. The Engineer is really the only "required" NPC as well because of doors and panels, so much of the game can be done while they hide and you clear out the rooms of Thing monsters.

I know this is not a super in depth guide as far as each section of the game, but if you follow similar strategies to what I have outlined here (take your time progressing through the game, keep your squad "safe" as much as possible, and abuse the save system frequently) then you should have no problem getting the achievement to pop by the end. The achievement unlocked for me right after the last cutscene after the final boss achievement popped and before the credits rolled.

I hope this helps clear up what you have to do, as I was a bit confused myself going in what this achievement would even entail. Please do not dislike the solution unless you state why in the comments, thank you!