Anti-Climax Boss: Both of the "true" final bosses pale in comparison to the fight against Dr. Purnell earlier. The final boss for the bad endings, Wheelchair/Sick Simon, does nothing but spawn goons and use telekinetic attacks, both of which are easy to deal with (as long as the player saved up enough ammunition), while the final boss for the good ending, Book Simon, is just a chase down a long corridor where you occasionally fire off shots.
Broken Base: Ever since Lowtax's very mocking Let's Play (which complained about the voice acting, the slow pace, the darkness of the mod, the puzzles, level layout, and the over-reliance on jump scares, on top of the LP overall really being an excuse to bash PewDiePie and the 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. It's bad enough that SA's Let's Play Archive has two LPs of the game on it now — one by Mr. Sunabouzu, a known fan of the team, that is rather respectful towards the game (at worst only being mildly sarcastic), and another by chocolatekake that was done for a bad games thread and gives it no respect whatsoever.
The Sawrunner, a masked man with a saw that rushes at you with erratic movements while screaming, and will hound you through various segments for the better part of the game even if you somehow manage to kill him at some point. He can instantly catch up to you 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.
The Sawcrazy is probably even worse. He's not as fast, but that's where the upsides end. He has two chainsaws, which he swings around at all times so even getting close to him is instant death, he's only slightly less durable than the Sawrunner, and unlike him, he's pretty much unavoidable. Thankfully, he only shows up in co-op.
For minor enemies, the Babies and Hangers. Babies charge at the player until they're in range, to which they stab Simon with a metal spike as their head explodes, causing a massive amount of damage to Simon. It doesn't help that most of the Babies in the game spawn in cramped, indoors locations, making running away from them very hard. Meanwhile, the Hangers are more "environmental threats" that drop from trees and damage Simon as he passes under them. Since the Hangers kill themselves in the process, all players can do is try to avoid walking under the trees that Hangers spawn from.
Enjoy the Story, Skip the Game: The game is well regarded for its amazing horror atmosphere but runs into trouble with its actual gameplay; mainly due to the somewhat clunky combat, extremely limited inventory space, unpolished movement and platforming mechanics, and abundance of Trial-and-Error Gameplay.
Game-Breaker: The Camera. It can freeze all non-boss enemies in place, and if you leave the map, the enemies despawn. Skilled players can eventually learn to abuse these attributes of the Camera to be able to play almost the entire game without needing a firearm, making Nightmare mode a breeze, and as long as an enemy isn't hidden behind a wall (physical or invisible) you can freeze them. The only downside to it is a bug where the camera will occasionally not freeze enemies, which is fixed by shutting the game down and booting it back up. It doesn't help that you get the camera by beating the game in under 2 hours 30 minutes, which only requires you to not get lost or leave something behind that you'll later need.
David Leatherhoff's Axe, as well. Like the Camera, you don't get it until the New Game Plus, and it requires finding it during Ending 5. Once you do unlock it, you have the strongest close combat weapon in the game. It deals 55 damage in one swing, enough to kill almost every enemy in one hit up to Normal mode, and swings incredibly fast. The only downside is that most enemies can get at least one hit in before you kill them... until you combine it with the aforementioned Camera, practically making even Nightmare mode an easy experience.
A small-scale one, but the Gas Mask the player earns after beating Doctor Mode. It allows the player to see without a light source needed, and unlike other light sources, it stays with the player throughout the whole game (even after Simon's Bag of Spilling moment, since it's not technically part of his inventory). It's a Boring, but Practical item, allowing the player to see in the dark during Chapter 4 and Chapter 6.
Heartwarming Moments: Simon occasionally gets texts from his mother expressing concern for his absence and asking for him to get home throughout the early parts of the game. It isn’t much but knowing that someone out there cares about you and is seemingly not in the same danger you are lightens the sense of loneliness and despair, if only by a little.
Narm: The English voice acting, Simon's in particular.
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 in the throat after you kill them is disturbing, the squishing noise the action makes is not. It sounds like someone stepping on a mound of pudding.
The flashback with Sophie after her suicide and the Carcass fight is hard to take seriously. Simon breaks down in public declaring his love for her, to which she seems mildly annoyed at best, not even paying attention at worst.
Nightmare Retardant: In co-op mode, a good deal of the horror factor can be lost after the first time you beat one of the terrifying monsters to death with nightsticks.
Melee combat isn’t very good. Enemies usually attack faster than you can go in, get a hit, and dodge so taking damage is pretty much unavoidable. Sections where you have no gun are some of the most difficult in the game as a result.
The game’s inventory system is painfully restrictive at only 6 slots and key items take up space (though thankfully ammo does not). There also isn’t any way to store items save for just dropping them on the ground somewhere and praying they don't despawn while you're off doing something else on the other side of the city. This problem is exacerbated from Chapter 5 onward when you permanently lose three slots.
Spiritual Successor: To Andreas Ronnberg's previous game, Afraid of Monsters, down to the jittery, twitching monsters, to the abstract and terrifying dream sequences. The game even has a Nostalgia Level in the form of "Heaven", which recreates the penultimate levels of one of Afraid of Monsters' endings, with neither David Leatherhoff or the Twitchers aesthetically updated.
Tear Jerker: All but one of the endings where Simon succumbs to despair and commits a Murder-Suicide involving him along with Sophia and/or Dr. Purnell.
That One Attack: While the Final Boss for the good ending route, Book Simon isn’t that hard, if a bit dependent on Trial-and-Error Gameplay, his Last Ditch Move where he lights a flare and charges at you with a sledgehammer can easily kill you at the last second. Not only are you essentially on a time limit since Sick Simon’s mobility is too crippled to be able to escape but he starts using this attack in a dark room and you barely have enough time to finish him off. To not die you not only need to essentially unload your entire mag into him as fast as possible, but also need to hope you don’t need to waste too much time lining up your shots.
Chapter 4 has an absolutely absurd amount of backtracking, practically to the extent of replaying the entire game up to that point, some of the most difficult encounters in the game, a bunch of difficult jumping puzzles, a sequence where your phone runs out of battery, forcing you to use flares, and topped off with a maze filled with instant kill enemies that love to ambush you from around corners.
Chapter 4 has a Nightmare Sequence in the return to the apartments where you need to fend enemies off in a very cramped arena (with a large hazard in the middle). Said enemies are extremely fast, are on the floor where they’re hard to hit, and come at you in waves. To add insult to injury dying means repeating the minute long hallway right beforehand.
Chapter 5 starts with an ambush of enemies and being forced to climb out of a train under a strict time limit, which is made extremely difficult by the game’s clunky platforming mechanics. Afterwards your left in a dark forest with your entire inventory, including half of your inventory slots, missing. On top of being restricted to melee for most of the chapter, the forest is confusing to navigate due to the darkness and confusing layout.
The Woobie: Simon is a bonafide example of this: A young man struggling with depression, suicidal thoughts, and self harming, his love interest not interested in pursuing a relationship with him and afterwards losing his legs after getting hit by a car drives him to the point of suicidal instability, with Sick Simon being the real representation of him in the real world at the brink of ending it all. All but one ending have him succeed in doing so.
