The Insane Difficulty is locked when first start to play this game. In order to unlock this mode you must beat the game or join a co-op game (the host only needs to have Insane unlocked).
You must beat every chapter inside of Act 4: The Long Road Home (in Insane mode) to unlock this achievement. There are a total of 8 chapters inside of Act 4 that you must complete. You are allowed to play the chapters in any mode: co-op, single player, or a mixture of both. The achievement will unlock as long as you have credit for beating each chapter in act 4 playing on Insane.
If you are having issues beating this mode by yourself I would HIGHLY recommend playing with a real person other then AI. It will make your progression through the game much easier however this is not a requirement. It can be done by yourself.
Here are all the chapters inside The Long Road Home (Act Four) and some help:
CHAPTER ONE - Campus Grinder - You will start this act by attempting to recover some maps from the Fenix mansion. Fighting inside the courtyard can be intense from the amount of enemies you are going to have to mow over. After you get to a certain point you are going to have to take out two boomers, so take cover and use long range lancer ammo or the powerful Torque Bow. You are going to come to a choice to pick a left or right route. The LEFT route is far easier.
CHAPTER TWO - Bad To Worse - You are now one step closer inside now. You are going to have to wait for Jack to cut open a door so why not do some fighting? Toss some 'nades over in the holes that open up and get ready to use the hammer of dawn on the two boomers that show up. Ok what's next?
CHAPTER THREE - Berserker - Once inside the greenhouse, ah yes at last inside, you really only have one enemy here, a berserker. Use your hammer of dawn to take this beast out. To do that you will need to dodge a few of her attacks and go back the way she came from, get to the area with some pillars that she will run into to open up some clear sky so the hammer of dawn will work. Two pillars will be enough if your quick.
CHAPTER FOUR - Hazing - I hated this part, you are now going to end up in fighting in another courtyard but this time your just going to fight wave after wave of the horde. There is only one hole to plug up and after that they are just going to keep hammering you until kill them off. I found it best to stay to the right side but others have told me just to stay in the doorway. You be the judge. Now after a massive amount of fighting and another boomer you will come to another route selector. I liked the RIGHT path better but they are pretty much the same.
CHAPTER FIVE - Close To Home - So close but so far away. Time to take out several drones and a few Theron Guards. Nothing too hard. After you get past them you are going to get to pick yet another route, I suggest sticking to the LEFT side, much easier. You will fight two Troika's (use torque bow and lancer).
CHAPTER SIX - Imaginary Place - At last you are at the steps to the house. fight you way up to the house and enter into the courtyard (yes, if you are counting that is three of them!) but this one you don't have to fight in, they will retreat and you will enter into the house. Once you do go left and plug a hole with a 'nade to help you out. Close combat here so stick to a shotgun. Move up stairs to clear it out, once everything that was moving is not any more just go back downstairs for a quick cut scene and an entrance to the basement.
CHAPTER SEVEN - Entrenched - If you can't find the entrance to your dad's super secret room, go to the back (the flooded area), the wine rack with wine in it will hide the room you seek. Once again Jack will be opening a door so while you wait why not kill some drones, should not be too hard, lancer/shotgun works great. When you are back out of the basement it will be time to get out. First your going to have to fight for your life. If you are playing co-op you can have one person sniping at the top while one person trying to hold the front downstairs (just have the guy sniping ready to save you if needed!) and if thing get a little insane just call him downstairs to help out. If you are solo you can stay in one of the rooms upstairs that only have one entrance and hope your partner does not eat dirt. Save your 'nades for this fight.
CHAPTER EIGHT - Moving Out - I have read forums where this was hard area to beat but every time I have played it I have passed it with little to no problems. Once you get outside you will need to RUN. Playing co-op? Even better, if someone gets downed and your not RIGHT there? Keep on moving, you only need one person to end this mission. Just get to the end and you will be saved by the cut scene. I prefer the left side.
If you are still having issues please look at these general tips:
- Use grenades to cover emergence holes up. This will allow you to stop the locus from coming. This equates to less enemies and less ammo you need to take them out. This is highly recommended if you are playing alone.
- Become good at active reloading. This makes the Locus drop so much quicker.
- Take more cover. Not only do you heal but the Locus do not.
- Work as a team (if your playing with a person) and try to aid your AI partner (he will help some but there are issues with him getting killed allot in certain areas).