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 1: Ashes (in Insane mode) to unlock this achievement. There are a total of 8 chapters inside of Act 1 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 1 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 Ashes (Act One):
CHAPTER ONE - 14 YEARS AFTER E-DAY - Easy, this is a training mission. Just stay back and use the hammer burst or lancer.
CHAPTER TWO - TRAIL BY FIRE - You should have no major issues in the first half (outside). I would get chainsawed allot so I recommend staying back and using longer range weapons such as the hammer burst or lancer. In the second part of this chapter (once you enter inside the building) you may run into some issues so I recommend carrying at least one grenade to plug up the hole and you also want to stay back (after plugging the hole) and take cover. I still recommend using the hammer burst or lancer in this area. If you are having issues getting past the second half of this chapter I have attached a video (first video).
CHAPTER THREE - FISH IN A BARREL - This chapter is fairly easy IF you do it correctly. The first challenge is killing the locus on the gunner turret. If you go on the right side and use the short tunnel to get to him it will make things much easier. DON'T USE GRENADES YET. The second part is where you will be inside a small area with four emergence holes. You will do MUCH better if you plug ALL four holes. If you are having issues please see the videos below (second video).
CHAPTER FOUR - FORK IN THE ROAD - The first part of this chapter is okay. I personally choose to take the left path so I would not have to deal with the gunner. The only real issue with the left is you will have to take out three locus in a small room with a slight hill. I stayed outside this room and shot them with a hammer burst (act quickly or they will rush you once in a while). If you want to take the RIGHT path check out the video below (third video) and make sure you have at least two nades. The second part in this level (also see the third video) was a major pain. It is the part after you meet back up and enter this larger room with a gunner on top of some stairs and PLENTY of enemies.. Since your NPC partners like to stay on the left side I would recommend going to the right side to take out the gunner and other enemies from a far (I used hammer burst but lancer works great too). Make sure you plug up the hole that comes up after you clear the enemies out of this room (it appears in the back where you entered) if you can't make it in time RUN to the gunner turret.
CHAPTER FIVE - KNOCK KNOCK - I stayed back and shot with my hammer burst and lancer during the whole chapter. Used my chainsaw in smaller areas. Or you can go rushing in like this guy in the attached video (see the fourth video).
CHAPTER SIX - HAMMER - COLE TRAIN BABY!!! One of my fav characters. This area is pretty straight forward. Stay back (use your hammer burst or lancer) even after you get the Hammer of Dawn I stilled used my hammer burst. Even though your mostly inside the rooms are fairly large which allows you to stay back. I recommend using the chainsaw while waiting for Jack to open the door (you can use the shotgun as the guy in the video shows - see the fifth video).
CHAPTER SEVEN - WRATH - The level is pretty straight forward. Stay back and use the hammer burst or lancer. You will mostly be inside with plenty of cover and if they start getting close you can chainsaw/shotgun them. During the last part (when you are outside on the balcony) MAKE sure you will all the locus on the balcony first then take out the ground support next with the Hammer of Dawn.
CHAPTER EIGHT - CHINA SHOP - The level is pretty much the same in all difficulties. You shot the berserker so he follows you, jump out of the way so he destroys the doors and once your outside hit him good with 4 Hammer of Dawns (you can also frag tag him if you have the guts... wanna see? Watch the last video).
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. I would recommend always carrying at least 1 'nade with you if possible (Thanks to Psycho Joe 1 for this!).
- 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).