Ballistic Discount: The gun store has a robotic gun that tracks the move of every customer. However, you can shoot the proprietor and the robot gun will not fire. Doing so does not yield any loot, however.
McCoy: You're in a desert walking along in the sand when all of a sudden you look down and you see a tortoise. It's crawling towards you. You reach down and you flip the tortoise over on its back. The tortoise lays on its back, its belly baking in the hot sun beating its legs, trying to turn itself over, but it can't. Not without your help. But you're not helping. Why is that?
However, the test isn't one-hundred percent accurate; sometimes asking or not asking certain questions changes the result, or causes the result to come back as "Inconclusive".
The Ingenue: Lucy Devlin is very much this, making her an unwitting pawn in someone else's plan.
Kick the Dog: That cute dog of yours? Don't expect it to live to see a new day.
Lack of Empathy: One of the Replicantss distinctive features, along with a planned obsolescence scheme.
What's especially chilling is that it's very easy to look at the situation in reverse; the replicants you are ruthlessly "retiring" are self-aware, sentient beings, capable of pondering their own identity and existence, begging the question: "Who really lacks empathy in this story?"
Mercy Kill: This is an option with Runciter, later on in the game.
Multiple Endings: There are thirteen different endings. What's more, it's not possible to get all of them from a single playthrough, as some of the variables involved are calculated when a new game is started.
The Nicknamer: Crystal does this to Ray, always calling him "Slim".
Non-Combatant Immunity: You always have a gun, and even when you can't use it, such as while climbing down ladders, enemies will refrain from shooting at you. Until the very second you climb off of the ladder. Still, it's the thought that counts.
Bullet Bob: Is that a .45 blaster under your coat, or are you just happy to be here?
Paused Interrupt: This can result in laughable scenarios, where a character is interrupted mid-sentence, by another character simply starting to walk towards them, waiting until they're next to them to begin speaking. Although, you'll be grateful for this if the guy you were talking to has a gun trained on you.
The Plan: Guzza, your superior, has one of these going that actually leads to most of the things in Act III.
What Measure Is a Non-Human?: A persistent theme throughout the game, made even more chilling by some of the VK results that come out as inconclusive.
What the Hell, Hero?: Killing Bullet Bob makes Ray wonder about this aloud; for even if Bob were a Replicant, he was a pretty fun and benign one.
What the Hell, Player?: Killing a character without confirming whether or not they are a replicant leads to Ray giving a short monologue about it, filled with philosophical and occasionally ominous/foreboding undertones.
You Dirty Rat: Rats really don't like your character, and have nothing but scorn for your desire to run around in sewers.