This guide shows the requirements for all the Achivements.

While this is not a walkthrough, it will contain some spoilers.
The mentioned loop number refers to the story walkthrough from Retr0:

Twelve Minutes | Step-By-Step Walkthrough

(In the new version of his guide the loop numbers aren't directly mentioned anymore. Just count them for yourself.)

This is one of the real endings, where you don't go (directly) back in the loop.

In one of the loops you have to talk with your wife about the red book she reads.
She starts to reads it on the couch and later on the chair in the bedroom, if you not trigger any other event in the beginning of the loop.
At the end of the game, when you get to the second sequence with the father, you have to click the red book in the shelf behind you and then just wait for the monologue of the father to end without clicking anything else.

This is one of the real endings, where you don't go (directly) back in the loop.

At the end, when you get to the second sequence with the father, you have to watch on the clock, when it hits 12 o'clock.
To get the time for this, first let him talk long enough (something more than a minute) until he threatens you to hit you. Then click on the red book (see number I) in the shelf behind you and wait the rest of the time while watching at the clock.

This is one of the real endings, where you don't go (directly) back in the loop.

At the end, when you get to the second sequence with the father, choose to leave the daughter alone.

The game is not over, as you can get the watch back from the vent in the bathroom and turn it manually on 2 minutes before 12. This triggers the second father sequence again. This is necessary for number IX.

This is one of the "loop" endings, where it seems to resolve everything in a way, but after them you are back in the loops again.

You have to find out everything and be after the first sequence with the father aka the "final" loop.
Talk to your wife about the past and what really happend. Then choose, that you are the killer, say it is your fault and that you will confess.
Then trigger the cop to listen by calling her daughter an say your wife is innocent.
Also grab the watch.
In the later conversation with the cop, when your wife points at you, say you are the killer and that it is all your fault.
Tell him about the watch and after he is gone and your wife locked herself in the bathroom just leave the apartement.

Having this done in a playthrough is part of the number XII.

This is one of the "loop" endings, where it seems to resolve everything in a way, but after them you are back in the loops again.

This can be done in loop 6.

When you wife sits on the couch give her a mug with sleeping pills.
When she goes to bed turn the lights on and off in the bedroom, get the watch from the bathroom and the phone from the closet and then wait in the closet. After he knocked himself out handcuff him with one of his cuffs (take nothing else from him).
When he wakes up talk to him and say you will do cooperate. Then just do what he tells you.

Having this done in a playthrough is part of the number XII.

This is one of the "loop" endings, where it seems to resolve everything in a way, but after them you are back in the loops again.

This can be done in loop 9.

Away from your wife call the cop's daughter and tell her the reason why her father is doing this.
Then prepare the dinner by putting plates and filled mugs on the table.
Tell your wife you are ready for desert and after the baby suprise tell her it will be great.
Play along good/nice till the end.

Having this done in a playthrough is part of the number XII.

This is one of three painting related Achievements.

For this you have to view the painting in the bedroom at all of its variants.

Variant 1 (start of the game) - The couple stands on a balcony, surrounded with white flowers - beginning
Variant 2 (from loop 9 on) - Couples stands apart and the white flowers are gone
Variant 3 (after first sequence with the father) - the Man stands alone with monster in the background

To be save, just look at the painting in every loop. Btw. the changes are also visible in the normal game view.

This is one of three painting related Achievements.

For this you have to view the painting over the couch in all of its variants.

Variant 1 (loop 1) - two trees with green leaves
Variant 2 (from loop 2 on) - three trees with green-brownish leaves
Variant 3 (from loop 9 on) - three trees with only the left one with green-brownish leaves
Variant 4 (after first scene with the father) - three trees in snowy environment

To be save, just look at the painting in every loop. Btw. the changes are also visible in the normal game view.

This is one of three painting related Achievements.

For this you have to view the painting right beside the window in the living room in all of its three variants.

Variant 1 (loop 1) - simple egg
Variant 2 (after the first scene with the father) - an eye is visible at the top of the egg
Variant 3 (after going back in the loop from being alone - see number III) - a snake biting its own tail is seen

To be save, just look at the painting in every loop. Btw. the changes are also visible in the normal game view.

This can be done on any loop.

Just get one of the mugs, fill it with some water and use it on the flower.

This has to be done on a fresh start of the game after the small tutorial sequence.

Just don't do anything after entering your apartement until the sequence ends.

The flower has to grow three blossoms.

One of each blossom is "rewarded" for reaching/playing one of the three "loop" endings described in number IV to VI.

Until you reach the three blossoms, don't forget to give the flower a cup of water in every loop.
When it has all three blossoms, you have to water it one more time.

If you have problems with this way, look in the comments, as there are some hints, how other recieved this Achievement.