Disco Elysium is an RPG where you're never alone. Not because your buddy cop Lt. Kitsuragi won't leave your side until 9pm each night—at which point you can pretend to go to bed, then sneak away to take drugs and steal the boots right off a corpse—but because from the first scene you've got a chorus of voices in your head.
Some of them are parts of your brain: The Ancient Reptilian Brain and the Limbic System are in constant conversation when you try to rest. But most of them are just whichever skills you've put the most points into. I had a decent score in Drama, which meant that I could sometimes tell when people were lying or telling the truth, but it manifested as the voice of a wanky Shakespearean actor. "Prithee, sire! I do believe he dares to speak mistruth!" That sort of thing. It also tried to convince me to lie about the serial number I'd found on a piece of evidence, because that would be more fun.
Meanwhile, the Authority skill barks with the voice of a military sergeant, saying I should interrogate everyone with force, while Physical Instrument is an inner football coach telling me to get into shape and Electrochemistry is a louche debauchee who thinks I should drink more and smoke cigarettes for "massive bonuses".
It's like carrying around a full party of BioWare companions. "You should drink that wine you found in the street," is definitely something Varric would say. I'm the player who chooses companions based more on their personalities than their stats, so Disco Elysium is perfect for me. It's never going to limit me to a party of three or six or whatever. There's always room for more voices in my head.
Some of the skills go beyond this role as individual NPCs and become entire populations. Putting points into Empathy means there's another layer in every conversation with actual people, letting me know what they're thinking and what their body language suggests. Encyclopedia on the other hand is a skill that recites trivia—massive deluges of it. If you are into "lore" this is the skill for you, but if worldbuilding bores you, it'll drive you nuts.
While Empathy lets me know what other people might be thinking, the Inland Empire skill gives interiority to objects. If you play Bloodlines as a Malkavian there's a great bit where you argue with a stop sign. In Disco Elysium, with enough points in Inland Empire you can talk to everything from a mailbox to your own necktie.
Esprit de Corps adds another chorus. This skill, which suggests what a proper cop would do in any given situation, gives insights into what other police are doing right now. These blue visions might be real or they might be imaginary. After radioing my precinct to explain how disastrously my investigation was going, Esprit de Corps chimed in to recite the conversation among my coworkers about what a fuck-up I was, a flash of cop fiction what was funny and bleak and one of the most impressive bits of writing in a game where every five minutes there's another contender for 'most impressive bit of writing'.
One more I can't skip is Shivers, a seemingly useless skill that represents your sense of the city of Revachol in which you live. Every now and then it narrates a vignette at you, colorful moments in the lives of people nearby. But then, after taking speed to increase my stats so I'd be better at dancing, I fell into a lucid dream in which I had a conversation with both my own spinal cord and the city itself. This is just the kind of thing that happens in Disco Elysium.
Giving skills and other aspects of who you are their own voices makes it a weird and wonderful Inner Monologue Simulator, in which the path toward truth is slicing yourself into aspects—entire hosts of devils and angels—and letting them interrogate you and each other. At one point I made my Rhetoric skill apologize for trying to get me to ask a question whose answer would be too painful to deal with.
The actual NPCs are great too, and I should give a shout-out to Kim Kitsuragi, the long-suffering cop who gets partnered with you and has to put up with your shit. He's one of those classic characters who reveals more facets as you get to know him. But where another RPG might give you a party of characters with dark secrets to uncover, in Disco Elysium you're the one with secrets and an army of mind people alternately trying to hide or reveal them.
It's exaggerated to suit your situation as one troubled individual, but there's truth to it. Maybe "everyone contains multitudes" seems like an obvious point to make, yet living for hours deep inside someone else's crowded head has made it concrete for me in a way I won't soon forget.