The Great Perhaps

Here is my 100% Achievement guide for The Great Perhaps.

A little bit through the game, you end up in a hospital/Mental ward.
We need to get the key from the guard on the first floor.

Go to 2nd floor and into the past you see a patient drawing on the wall. Here a cutscene will happen.
Immediately go into the future as to avoid being injected by the member of staff.

There is a gurney and blood splatter on the wall in the future, so grab the sponge and throw it sort of inbetween to get the big insects to come down.

Go to the 3rd floor, staying in the future and there is some huge ass flower to interact with. Doing so gives off a big pink stink where you can pick up a flower.
Into the past and the old guy talks to you wanting to go to the 4th floor, so push him to the right, avoiding guards as you go, hit the elvator button and take him all the way to the left.

Once that is done, head up to the 5th floor, in the middle of this area is a desk, interact with ti to put the flower in and the nurse thinks its the guard downstairs and voila, job done!

Go to 14:25 to see where and how to do this.

Hope this helps!

In the hospital, you need to get to the roof. To do that, you need to get the key from the guard on the first floor.

Phase forward, then go up to the 2nd floor. On the 2nd floor is a patient drawing on the wall. Phase forward/back to get the red sponge he was using. Go up to the 3rd floor.

On the 3rd floor is a man on a gurney. He wants to get to ward 11, all the way to the left on the 4th floor. There are some bugs in the way. In the future, stand to the right of the bugs and throw the red sponge to the left at the bugs. Phase back, go all the way to the left, then phase forward. Use on the giant pod to get the red flower. Phase back, and move the man on the gurney right to the elevator, phasing as you need to so you avoid the nurse.

When you get to the elevator, take it to the 4th floor, then move the patient all the way to the left. He'll tell you the nurse on the 5th floor likes the guard on the 1st floor. Take the red flower and put it in the vase at the nurse's station on the 5th floor. She'll run downstairs and take the guard away, and you'll get this achievement.