Insane mode is the hardest difficulty. It's Nightmare difficulty with no checkpoint or saves. This will require you to finish the game without dying and you have to do it in a single sitting. You can pause the game so if you need a break for any length of time, you can do that. But if you die at any point in the game, you will respawn right back at your car in the beginning of the game. If you die from a failed jump, you will have to start over.
Since Insane mode uses Nightmare difficulty, you should practice all the difficult sections of the game on Nightmare before starting your insane run. Nightmare/Insane differs from Normal in the following ways:
The maximum number of extra batteries you can carry is 2.
There are fewer batteries that can be picked up.
The Variants move faster and react to noises quicker. They are much smarter.
Strong Variants (Chris Walker, Dr. Trager, Walrider) will one hit kill you. Weaker Variants will kill you in 2 hits, with the exception of a couple who will one shot you.
After you have beaten the game for the first time on any difficulty, you have the option to select a chapter and then select difficulty. Use this as a tool to learn the more difficult sections on Nightmare. Progress to the section you struggle with and create a save point. Replay the section several times until you feel that you can pass it with no issues. Continue doing this for the rest of the difficult sections. Once you feel comfortable that you can survive without dying, then it's time to select Insane difficulty from the new game screen at the main menu. But practice is key and doing it on Nightmare with checkpoints and the option to save will best prepare you.
Also make sure you manage your battery power. There are far fewer battery pickups but as long as you don't use the night vision unnecessarily, you won't have any issues. Just remember that you only have to turn it on for no more than a second or two at a time to keep you pointing in the right direction.
In regards to battery management, if you have the maximum two spare batteries on you and come upon one you can pick up, replace your used battery that is in your camcorder currently by hitting and then pick up the battery you found. This will give you a full battery in the camera and two full spares. Here are some locations of batteries in the game.
Admin - Right after entering the asylum and squeezing through your first gap. It'll be in a drawer in the first room on the left. This will give you two full spares as you start with only one.
Prison - There's two you can grab here. You can find a battery in the area with the first encounter with the variants. This will be in a room behind the guy who is behind the glass beating on a corpse. You can safely enter this room before hitting the button if you keep your distance from the guy there. There's another one near the room Chris Walker comes breaking into and you need to jump into a ceiling vent. It'll be next to the inactive door in the hallway outside the room. Just get it before hitting the button.
Sewer - Just past the room you enter with the guy you need to record for a note. Before going into that room, continue down the path and you'll find one on the ground next to a corpse.
Male Ward - Near the end of the chapter, before climbing into the window of the burning cafeteria, continue down the hall, turn right and it's in the first room on the right.
Courtyard - Don't be afraid to use up all your batteries in this chapter, there are plenty in the Female Ward. There's a couple here in the Courtyard. First one is before dropping down to the final area with the gazebo. It'll be next to a guy standing at a dumpster and the second one will be on a bench at the blood fountain right before entering the female ward.
Female Ward - There's five and if you used all your batteries in the Courtyard, you're in luck. Two will be near the beginning. Right after entering the chapter Father Martin will talk to you. From this starting room, instead of turning left into the next hallway, turn right and it'll be in the dark next to a body. One will be in the back corner of the room with the wheelchair in the dark near the locked outside doors. The third one will be between the two back rooms where you need to get the fuses. It'll be on a shelf. The next one will be after getting the key and it's on a table in front of you as you walk up to the third floor. The final one will be on a nightstand in the room next to where you dropped your camera. Save this for the return trip if you can.
Return to Admin At this point you shouldn't need any more if you have 2 spares. One will in the room where you open the door to the projector room in the theater area only to have it closed on you and the other will be down the long hallway at the end in the area you need to climb out a window in the dorm area.
Remember these things when playing on Nightmare/Insane Difficulty.
Enemies will hear you more easily. Crouching and opening and shutting doors slowly will make less noise.
Hiding will not work if they see you hide. So if you're being chased and enter a room, close the door behind before hiding.
Gaps you squeeze through are the best way to lose Chris Walker. He's far to fat to make it in, however, he will reach in so make sure you aren't to close. Also, when avoiding him by entering small tunnel holes, he will reach in there if you are to close. So keep back.
Enemies are fast, but you are faster. Keep holding to sprint. Sometimes running is the best strategy, especially if the enemy can't insta-kill you if you get hit. Read the specific chapter by chapter difficult section below for specific encounters.
Watch the video below for a spreedrun where I talk about each section as I come across them offering the tips in this guide and show you how to apply it within the game.
Difficult sections you should consider practicing
Chapter - Administration Block
Who didn't pay the electric bill - The only difficult section in this is the basement when you need to restore power. As soon as you turn on your first gas pump by hitting the button, you will have a local variant break down the door and enter the room and will continue patrolling this room and the hallway from which he came. This lone guy won't kill you in a single hit so if you do meet him in the hallway or the room where the breaker is, you can sprint back to the main control board, hit the button, and make a quick getaway back upstairs. But to do that, you will need to pass him far enough away from where you turn on the power, ideally in the back hall or the breaker room.
Chapter - Prison Block
Open Sesame - After dropping into the hole where the inmate was painting on the wall, you will need to push a button in the back room to open your get-away door. There will be a variant standing around in this section who will not kill you yet if you keep your distance. When you open the door leading to the button, you will have someone else waiting for you and he'll start chasing you. You can run all the way back to the room next to where you jumped down into the area. Close the door behind you if you need the extra precious seconds to hide. Once he gives up looking for you, he'll exit the area completely and you'll just have the one last guy who was leaving you alone. However, once you press the button, he'll come after you. You can just simply run past him because it'll take two hits from him to die.
That's some pile of bodies - Further into the level, you'll fall to a lower section due to an explosion. This will leave you on a large pile of bodies in a dark area. You need to climb the stairs at the other end of the room but at the top of the stairs Chris Walker will be waiting for you. If you're quick, just before the top of the stairs you can hop over the railing to the right and run along the outside of the cell block.
Chapter - Sewers
How many Chris Walkers are there? - In the area where you need to drain the sewers, you will need to find two valves to turn. In the main room there is a path to the left and to the right. Chris Walker will also be patrolling this area. Run down the right path and you'll come to a room with the first valve. As soon as you turn it, Walker will be coming for you and eventually into the room. You can either hide locker or behind the shelving in the right side of this room in the dark. Wait for him to come into the room and then walk away. Give him a few minutes and follow him down the other path. Keep your distance or he'll come back for you. When the coast is clear, you can squeeze through a gap that leads to the second valve. He can't get you here because of the narrow gap. Once that job is complete, wait for him to walk back to the main area and once the coast is clear, jump down into the lower sewers. Patience in this section is rewarded.
Don't drown - In the lowest sewer levels where it's flooded to your waist and completely dark, you will find a tunnel passage with the bottom of a fence cut out for you to squeeze into. In this room, you'll see a light on the ceiling and that is your exit. Be careful navigating to this because Walker will be walking around the center of this area. You can keep your distance from him by pathing around to the left around the outside of this area. Once you get close, you can jump up to the catwalk near the hole and then from there you'll need to jump to the suspended ladder.
Chapter - Male Ward
Chase is on - During the chase scene, make sure you don't miss the jump you need to make towards the end. To make sure you jump at the last moment, look down because your character's perspective may make you believe you are closer to the edge than you are and you'll fall short and die.
Still have my middle fingers - After the 5 minute cut scene with Dr. Trager, you will enter a room with one of his patients. Just wait in the dark to the right of the door and wait for him to walk into the room towards the patient and then exit the room and turn left and run to the ceiling vent you can climb into. The second section with Dr. Trager will be more difficult. Once you dropped down from the vent, open the nearby gate after moving the object blocking the door but don't go through there yet. Go down the hall to the first large room on the left. There will be a set of doors in the back of the room that lead to another large room. Just open the door that joins the room and then turn around. Trager should be pathing into the room and will see you. Now head through that door you just opening and into the next large room and exit out of this room and head left but make sure you close the door behind you first. You will have plenty of time to unblock the door you must next go through. Further on, you will drop down another ceiling vent and need to take a key. Take it, but head into the nearby large room and hide behind the door once again and wait for him to run in the room and past you. At that point, go back to the room you got the key and exit the door that was to the left of it.
Walker needs a shower - In the section where you need to activate the sprinkler system, pay note to the squeeze gap you used to enter the area, and a second one in the back left of the big room. These are the best ways to get away from Walker who will be pathing around. You can sprint into this area right away and head to the room with the valve to the right (not where the squeeze gap is). As soon as you turn this, Walker will be heading your way. In the small room right before the valve room, there will be a white basket along the wall. You can hide behind that and wait a minute or two. Walker won't come into the room and eventually he'll give up his search and head back out to the larger room. Make sure you give him a minute. Once clear, make it back out the larger area in the center and if the coast is clear, sprint to the squeeze gap taking you to the second valve. Now you just have to make it back to turn on the sprinkler. If you do see Walker or get spotted, you can use the large open area to get around Walker and make a run back. Before going to turn on the sprinkler, make sure you lost Walker or he'll get you. Use the squeeze gap that you used near the beginning of this section to lose his tail. Once clear, turn on the sprinklers and sprint back to the cafeteria.
Chapter - Courtyard
Big Fucking Guy - This short chapter only has one thing you need to worry about (two if you include battery life so be certain of the route). That would of course be Chris Walker. There's a section halfway where you'll drop down from a ledge you strafed along and you'll need to climb up some pallets with a bunch of white propane tanks around it. You'll see a light shining on it so you should see it. Sounds easy enough but Walker will be in this area and in the dark he'll sneak up on you pretty quickly. As long as you stay along the outside wall from where you dropped down to the spot you climb up, you should be able to avoid him.
No Picnic at the Gazebo - The second challenge will be the final section with Walker where you need to take a lighted path and climb through a small hole. While technically possible to sprint to this hole without getting hit, you're taking a big chance. Instead, let him spot you and then run back and there will be a gazebo and I found just circling the outside of that counter-clockwise that I was able to get enough distance from Walker and not get disorientated in the process.
Chapter - Female Ward
Another damn key!! - In my opinion, this is the last hard chapter. The first challenge will be when you get to the section with the 3 fuses. In this area, there is 3 exit points to the room. The window you came in from, a window on the opposite side and then a door. The window you didn't enter from will take you to a room and the door exit will lead to a hallway with a room on each end of it. When you grab your first fuse, expect a quick moving and aggressive variant. I found that going to the single room through the window, taking the fuse and waiting for the variant while hiding under the bed to be a good strategy. When he comes into the room, wait until he goes to the opposite side from the door and quickly get out from hiding and run out of the room while closing the door behind you. This should give you enough time to quickly sprint to each of the final two rooms. But be careful when going back after getting your next two fuses. You will probably meet the variant and need to run back to one of the rooms and hide. This guy won't kill you in one shot, so if you get hit and react fast enough to run away, you'll be ok. If all else fails and in an emergency, run out the window you entered from and run back to the previous area and he won't follow you.
After placing the three fuses and hitting the laundry chute button, don't wait for the key to drop. Run back downstairs right away. Be careful when running down the stairs to the first floor. There is a gap in the stairs and you need to jump across it or die.
3rd Floor - After going to the third floor you will jump across a gap and enter the room where the floor collapses and you need to use some bunks to get back up. A couple rooms later (after the note recording with the candles and the word "LIE" written on the wall) you will enter a room with two variants. When you open the door, you can quickly run right past them if you stay to the right. The exit door will be in the back right corner.
Lost and Found - After picking up the camcorder after dropping it through the floor, you will need to make your way back up to the third floor. But you'll be doing this in a rush as there are variants chasing you. The best way through this is just to memorize the path. If you get turned around and lost, you risk immediate death.
Chapter - Return to the Administrative Ward
Walker Hunt - There are three potential death areas. The first is right at the beginning where you will go down a hall and you'll see Chris Walker knocking down doors on the far end of a long hallway. If you quickly just sprint forward you will find a door cracked open on the left that leads you to the ceiling vent that you use to escape. Don't hesitate and don't worry about any of the other rooms.
Movie Time - In the theater, after getting the key from the upstairs office, a variant will come busting down the theater exit doors. Just hide in the dark next to the door and he'll run into the room giving you plenty of space to run out of the room.
God Help Us -The final challenge will once again involve our friend Chris Walker. After watching the scene in the chapel with Father Martin, you will climb into and drop down a vent. When you drop down you will see Walker at the end of the hallway. Where you first see him, you want to go through the door just to his left. But he's coming at you first. So quickly go down the hall just to your right and on the right is a bathroom. Enter the bathroom and hide to the right in the darkness. Chris will look for you in the bathroom and leave and will start busting down doors to other rooms looking for you. While he's breaking into other rooms you can leave your hiding spot and book it to the room at the end of the hallway you first look down. He may, or may not hear you and come chasing after you so quickly enter the dark room and look for your vent exit on the left side of the room.
Chapter - Underground Lab
Walrider... Run!!! - This chapter is all about speed. Just keep your finger on the sprint button () and you'll make it through just fine as long as you know where you're going. The only minor issue you will come across is when you shut off the life support system. Once you turn that valve, Walrider will come chasing after you. Your goal is to make it to the electrical panel box but the Walrider will chase you to just before that. Don't think you're safe when you squeeze through a gap. The only thing that will stop him is the decontamination chambers. The only other thing that can kill you is the jump across a large gap at the top of the long staircase section. Be careful not to jump to early, you can die here and you're just a minute from the trophy. After taking out the electrical, it'll just be a short run back to the start where you need to hit a control panel near where the pod's are at.