To move forward with this unified design, Valve sought a game designer, but found no one suitable for the job. Instead, Valve decided to create the "cabal", initially a group of six individuals from across all departments that worked primarily for six months straight in six-hour meetings four days a week. The cabal was responsible for all elements of design, including level layouts, key events, enemy designs, narrative, and the introduction of new gameplay elements relative to the story.  The collaboration proved successful, and once the cabal had come to decisions on types of gameplay elements that would be needed, mini-cabals formed from other departments most affected by the choice were formed to implement these elements. Membership in the main cabal rotated, since commitment required created burnout .  The cabal produced a 200-page design document detailing nearly every aspect of the game. They also produced a 30-page document for the game's narrative, and hired a writer, novelist Marc Laidlaw , to help manage that script for the game to assure in-game consistency.   The soundtrack was composed by Kelly Bailey. 
The autism spectrum is not a mental illness in difference to schizophrenia, and does not include symptoms such as hallucinations. It can be crippling, but it is in no way a disease. It is to be considered more of a neurodiversity, since it does in no way make a person sick, most of us are more sane and rational than others in fact, and it’s an insult and inaccurate to pile it together with mental illnesses such as schizophrenia. I am here to do some digging about schizophrenia due to my neighbour who is schizophrenic, and she is making my life a living fucking hell and she refuses to get help. The sounds from the other side of the wall makes the hair on my skin stand up.. It’s like living next to the Exorcist movie, (her voice sounds deformed at times, scares the shit out of me!) and with me being so sensitive, she is infecting me with her insanity, frantic screams and conversations with her voices and etc. You can hear everything here. She leaves notes in my slot, first one was about her explaining that she has an illness with voice hallucinations, and now today she left a letter saying she is having spirits visiting her that she cannot control, calling herself a soothsayer, clairvoyant, seer or what you like. Im translating it from swedish to english and there’s no proper word. My mom is a psychic, i believe and know that the spiritual realm exists, but what this girl is telling does not add up. A psychic person or a self proclaimed medium does not spend all day screaming and tormenting her neighbours, that is just pure insanity. She is sick and needs help, but refuses to get it. Instead she justifies this with different stories from time to time, maybe she doesn’t believe she is sick and pretends to take her meds, cause i called the cops on her once and i heard she told them that she takes medication, and then she left with them. I keep a close eye on her cause she really worries me and make my life hell, so i try to keep track on her, especially since no one barely seem to visit her. And when somone does visit her, she is talking so loud, basically screaming, being as overly nice as she could be, as if she was on drugs. Maybe she is. And i hear how she lies to them, saying how good she is doing. And then they leave, and the same minute she closes her door after her, she goes back to her schizo screams. It’s devestating to even just listen to. I feel sorry for her and at the same time i hate her. She thinks it’s ok to live here and act the way she is doing. She needs to move and she needs to get help. But refuses to spare me and other neighbours, or helping herself. She wont fucking let me sleep.