These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Base Breaker: Ever since Lowtax's heavily critical Let's Play (which complained about the voice acting, the slow pace, the darkness of the mod, the puzzles, level layout, the over-reliance on jump scares, and was really an excuse to bash PewDiePie and various "stick a camera to record my scared reactions" copycats that propped up around the game in the wake of it all), there's been a growing hatedom amongst the goons.
Demonic Spider: The Sawrunner, a masked man with a saw that rushes at you with erratic movements while screaming. He can instantly catch up to even if you sprint and is a One-Hit KO if he hits you. Even worse in the harder difficulty settings where he doesn't pause before attacking.
Hell Is That Noise: It is a game with a great soundtrack, but the track Kill Yourself is one of the more horrifying songs that play. It triggers when the world around Simon swiftly changes to a nightmare, and the song is downright psychotic.
Narm: The English voice acting, Simon's in particular. To a ridiculous degree.
Simon's voice is an interesting case, in that when the actor playing him joined the project and recorded some of the lines that are heard early on in the game, he was very new to voice acting, and his delivery was pretty iffy. By the time the game was in its finishing stages, he had done other jobs and, thus, gained experience, making the acting progressively less narmy as you play the game. And even before the end, the acting has its moments.
While the female enemies stabbing themselves after you kill them is disturbing, the squishing noise the action makes is not. It sounds like someone stepping on a mound of pudding.