Okay, so I just picked up the strategy guide for this game, and it had a little table that details this achievement. In a nutshell, you need to complete the game in the most EMPATHETIC way possible. There is a way to determine your empathy which I will put into spoiler tags, as even just glancing through the book I saw some things I kind of wish I hadn't. It's worth mentioning that the game is really excellent and will require multiple playthroughs to complete anyway, so it might be best to leave this achievement until a later playthrough as to not soil your first run on Prey.
That being said, this spoiler table details the most efficient way to earn the achievement:
*** Spoiler - click to reveal ***"The game uses a point system to determine your empathy, and you need at least 4 points to earn the achievement.
The most efficient way to earn the achievement is to:
Save Aaron Ingram
Save Dr. Igwe
Save Sarah Elazar
Save Mikhaila Ilyushin
Save Alex
You can apparently achieve a "psychopath" status by killing Sarah and her officers, OR by killing Sarah, Dr. Igwe, and Mikhaila, which will make the achievement unobtainable.
...And this spoiler will detail all the ways to add and detract from your empathy points, if you want to have more choices available to you.
*** Spoiler - click to reveal ***DETERMINING EMPATHY
You can earn one point of empathy by doing any of the following:
Save Dahl (Incapacitate Dahl Completed)
Rescue Dr. Igwe
Save Alex Yu
Complete Dahl's Ultimatum
Assist Mikhaila Ilyushin Completed
Mikhaila's Father Completed
Escape Attempt Completed
Gustav Leitner Completed
Help Luther Glass Completed
Danielle Sho Completed
Save 10 Mind-Controlled Humans
However, you can also LOSE empathy points by doing any of the following:
(-100) Achieve Psychopath status
(-1) Kill Aaron Ingram
(-2) Kill Alex Yu
(-2) Kill Dr. Igwe
(-2) Kill Mikhaila Ilyushin
(-2) Kill Sarah Elazar
(-1) Allow Dr. Igwe to die in Talos I Exterior
(-1) Allow Mikhaila Ilyushin to die in Power Plant
(-1) Allow Sarah Elazar to die in Cargo Bay
(-1) Allow Aaron Ingram to die in Psychotronics
I hope this helps those of you looking to grab this who may have missed it on their first runs, or if you're like me and couldn't resist the temptation to see what it was all about!