Node Monsters
There are 5 different Node monsters that you'll encounter during your playthrough, each with its own detail that makes them unique. When they spawn, they will give off their respective indicator before taking a few seconds to reach the room that you're in. They will follow a path so as long as you are far enough away from the main path, you are safe. Hiding in a locker will also protect you from the Nodes if you don't have a spot you can get far enough away. Angler is the most common of the five and has an anglerfish-like appearance. You can tell by the lights flickering and a screech that Angler is coming. Blitz resembles a viperfish and has a distinct screech, also being much faster than its counterparts, giving you less time to hide. Pinkie also resembles an anglerfish and has what is similar to a high-pitched scream. She does not flicker the lights so you'll have to always be listening out. Froger resembles a mix of a frog and anglerfish and emits a loud low-pitch gasping sound when it spawns. As it rushes through the room, it'll bounce back and come back the way it came before returning. It can do that twice before finally leaving. Chainsmoker is the last of the five and looks like blobfish with green smoke coming from its mouth. It takes longer to go through the room, but as it passes, it will release green smoke into the room, forcing players to leave lockers if that's where theyre hiding.
Eyefestation
Eyefestation is a shark-like entity that has many eyes that appear green. It'll spawn in the water outside the glass of the room and will have a green beam try to force you to look at it. Looking at Eyefestation will make you take damage and when you die, there will be a small jumpscare featuring Eyefestation. Walking to the next door and opening will get it to despawn and you are able to progress without the beam trying to force you to look its way. However, if you are carrying a flash beacon, you are able to flash it and it'll be stunned for just a second before it starts its beam up again, but it'll be much harder to keep from looking at it once it has been enraged. An indicator of this is that the green eyes and beam will now be red. There is another stage of its anger and that is if you flash it again. It'll be stunned once again, but the red will turn blue and make it very difficult to not make eye contact. If enraged, it'll keep the enraged tier throughout the rest of the game and spawn more often in glass rooms.
Squiddles
Squiddles are black squid-like creatures that normally only spawn in dark rooms, making them hard to see unless you get too close to them or you shine a light on them. Both are something you should not do as it'll aggravate them and attack you, causing you to take damage. Having a flash beacon on hand is helpful to have on hand as the flash from it won't anger them and it can temporarily light up the room so you can navigate better. As long as you move fast enough away from the squiddle, then it wont anger enough to attack you. You can tell when it has been angered because they will have a while face appear on their head.
Puddles of Void-Mass
Puddles of Void-Mass are entities that only spawn inside of lockers. A way to tell if one is in the locker is if you look through the upper slots of the locker and can see purple shapes through them. When opening a locker with a Puddle in it, you will see what looks like a few purple eyes and black void tentacles will appear and grab you where you are. If with a friend, then your friend will be able to rescue you if not too much time has passed, but if you are playing alone, then it will be an instant death.
Turrets
Turrets are a somewhat common encounter as you go through the facility and are controlled by another entity, Painter. They are similar to how they are in other games where if it detects you, then it will try to shoot at you. You can hide behind objects to block its attack, but there is a switch in the room where if you can reach it, it can turn them off in that room. After shooting enough bullets, it will take a few seconds for it to reload before it can continue on scanning the room.
Good People
The Good People is a mass of flesh with a white mask that is hidden behind fake doors. During a playthrough, there will be some rooms that have multiple doors that will show the same room number. Painter, another entity, changes the screens near the doors to show the correct door number by the fake doors to trick you into going through a fake door. Only one of them is the correct door and behind the others, Good People can be hiding behind it. If you open a fake door, Good People will turn and attack you before closing the door once more. You can avoid choosing a fake door by watching the screens and see which ones have a spark or if you are close, but also far enough away, you can listen for sounds that can indicate that it's a fake door.
Parasites
Parasites are small entities that will attach themselves to you if you are swimming out in open water. You will see them start to crawl on the glass of your driver helmet until there is quite a few covering your screen. The only way to avoid parasites is to follow the path and not stray off, but once you have them, the only way is to shake your mouse as if you were to try and shake them off.
Pandemonium
Pandemonium is similar to the other Node monsters, but it also different in the way it behaves. When approaching, you will hear a type of music and may take a little longer to appear than the others. To hide from it, you need to make sure that you are fully hidden. If you can see it, then it can see you. You are able to hide in a locker from it, but it will start a mini game that you will need to play through if you want to survive. Pandemonium isn't as common as the other Node monsters and has a pretty low spawn rate, but it's still likely to spawn at least once in a playthrough.
Searchlights
Searchlights are large monsters that you encounter as boss battles. There are two instances where you will encounter them, the first being about halfway through, needing to repair generators to open a door, and the second at the end of them game, where you need to repair large wires to get the drill working again. The first boss battle only has one spawn, but in the second encounter, there is about 3-4. They have four orange beams that they use as search lights to search for you. When a light shines on its victim, it will shoot a hook out to grab them and yank them back to it. Being hooked by a Searchlight results in an instant death.