This achievement will require excellent knowledge of the game's map layout and enemy mechanics. Do not be too alarmed by the ratio. It is a difficult achievement initially but once you understand the game it becomes easier. Obviously, you cannot reload your camera at all. Once you know the levels well it will be doable, but you need to prioritize your night vision use. Never use it when there is no threat. I only ever used my battery when I was being chased by an enemy. I got the achievement on my 3rd real attempt with one quarter battery left, so there is room for a little extra battery use.
The most important information is relating to the enemy types. There are 5.
1. Ordinary insane patients. These will appear in some levels and are the weakest of all. On insane difficultly you can absorb 2
hits from them before dying.
2. Chris Walker - Main enemy and very powerful. He is slow but can kill you in one hit. Use his slow pace to your advantage.
3. Dr Trager (Only seen in Male Ward) - Easy to escape once you know how, but can kill you in one hit.
4. The (naked) Twins - Powerful enemies, but only a major threat in Female Ward and Return to Admin. If you know how to avoid them you can get away from them 100% of the time. Very easy to pull off.
5. Walrider - Powerful, one hit kill. Only a threat in Underground Lab and can be easily avoided if you know how.
The video I used to walk me through the levels can be seen below. It's very helpful. I do not own it.
- There are certain areas in the game which will require many
practice runs due to the initial difficulty and layout. I would advise at least one full practice run on nightmare difficulty plus the following:
Admin Block - The part where you turn on the power is difficult due to the darkness and narrow layout. Definitely needs a few practice runs.
Prison - Relatively easy level, but the one part after being flung from the explosion might be difficult as Chris Walker spawns immediately after you get up.
Sewer - The majority of the sewer part is easy, apart from the very end where you go into the huge dark pool with the ladder in the middle. This requires perfect navigation and thus should be practiced many times.
Male Ward - Most of it is easy but you should know how to lure Trager so he doesn't catch you.
Courtyard - This is the hardest level in the game in my opinion
. The entire level is dark so you will need to know this level perfectly. The 2 parts with Chris Walker are also quite difficult due to the darkness and thus you will need to know where to go and how to lure him away.
Female Ward - Not hard but it is very risky as the lures required are very close encounters. The darkness will throw you off in this level too.
Return to Admin - Relatively easy, but the Chris Walker lure should be practiced once or twice.
Underground Lab - Initially easy, but there is one part which may throw you off if
unprepared. This level should be practiced once, one for knowing how to get away from the Walrider and two for the part where you climb up a huge flight of stairs to get to the cables. After climbing the stairs, you will jump over and turn right. The next area is really dark and the Walrider will be right behind you. Now, at this point in the game you may not have any battery left, so you should know this area especially well and how to navigate it quickly in the dark. I say this because this part cost me a run, which sucked bad.