The goal of each level is to empty all of the boxes. The game has point and click controls. Initially clicking on a box will open it. Clicking again will remove an item which then must be placed somewhere. The paper inside the box will slowly reduce as you remove items. Eventually, once the paper is gone and there are no more items inside, a final click on the box will remove it completely. Almost all levels have several rooms which will contain boxes to be unpacked.
Turning on the accessibility option (covered at the start of the next page) allows you to place items anywhere in the room. This means you can literally spill the contents of each box all over the floor (as opposed to finding the 'right' place for each item). Your unpacking can be as ugly as you want - aesthetics don't matter, although if you suffer from OCD you might struggle with the mess...
Once picked up, the item should auto-rotate if it's possible to fit it wherever the cursor is. You can also manually rotate with 
. On occasion, achievements will call for you to interact with an item which is done by pressing , either whilst holding it or when hovering over it. Some items can be stacked up, others will fit on walls or hang on clothes hangers*. If you are running out of space, you can pick up an item then move to a different room with 
or 
. Most rooms are also a little taller than the screen, so you can scroll up or down for a little for extra space.
Generally, you should just be able to spill all the items out without too many problems.
*Clothes hangers deserve special mention. During the later levels you'll have quite a few to unpack and they can take up a decent amount of space. Take the time to put them on the hanging rack in the wardrobes, if for no other reason than to keep them out of the way.
BiLLzuMaNaTi from Achievement Land has created an excellent video for the completion which can be found in full here for those who prefer a visual guide.
Start by turning on the accessibility option. From the main menu, select Settings > Accessibility then select "Allow items anywhere" and confirm. This will not have any effect on achievements.
Back out to the main menu and select Play. The pile of books represent save slots. Press 
on the top one and enter your name to begin.
1997
Click on the two available boxes. Now you just need to unpack the items in the box. With the accessibility option turned on, you can place the items wherever you want, it doesn’t matter.
Press on each box to open them and then again to pull out an item. Move it anywhere in the room and press once again to put it down.
You’ll eventually unpack a Rubik's Cube. While still holding it, press repeatedly . The colours will change and eventually you will solve it, with each side turning the same colour - stop pressing at this point, otherwise you'll mess the puzzle up again. This unlocks:
Keep emptying the boxes. Once they are empty, a final click will cause them to disappear. There’s a third box to unpack once you empty the top one. An old Polaroid camera in this third box will unlock another achievement once placed:
Once all three boxes have been emptied, a star will appear in the bottom-right corner. Click on it to end the 1997 level and unlock:
Press to continue.
2004
This level contains three rooms and you can skip between them with and .
Start by heading to the bathroom where you can make some progress towards the one and only cumulative achievement. There are a total of seven toilets that must be flushed across several of the levels. Click on the handle on the right of the toilet cistern for Gotta flush 'em all 1/7.
Go back to the bedroom and start unpacking. When you come across a wooden artists mannequin, don't put it down just yet. Press until it is dabbing to unlock:
When you unpacked the Toaster, pick it up and move to the bathroom. Put the Toaster in the bathtub to unlock:
In the kitchen, the brown and white cookie jar must be put on the very top shelf to unlock:
Finish unpacking. Remember that if you run short of space you can open cupboards and drawers or move between rooms. Once all the boxes are empty, click on the star to finish the level and unlock:
2007
Start by moving to the bathroom and flushing the toilet for Gotta flush 'em all 2/7.
Go back the first room with the large mannequin and start unpacking. You'll unpack a blue cube-like console. Put it in the tv unit, in either of the the slots on the sides. Press whilst hovering over it to turn it on for:
In the small bedroom with the blue chair, you'll come across a green baseball cap. Pick it up and move to the dining room. On the top of the shelves (you'll have to scroll up to see) there are two decorative heads - one is empty so put the green cap on it to unlock:
Continue unpacking and once everything is done, click on the star in the bottom right to complete the level, unlocking:
2010
In the room you start in, there is a record player on a side table at the bottom of the screen, in the centre. Hover over it and press to turn it on, which unlocks:
Go to the bathroom and flush the toilet for Gotta flush 'em all 3/7.
Head to the kitchen for a slightly tricky achievement, albeit one that is close to my heart (mmm... coffee). You need to make some coffee by placing several items on the kitchen bench (the one with the sink). All the items are found in the room, so do this before you start to unpack any boxes.
The achievement should unlock when you move the items shown in the image below. They are found on the other bench, top-left and centre cupboards and in the second from the top drawer.
Next head to the bedroom. Open the wardrobe doors, then the second from the top drawer. Remove all the folded underwear from this drawer, placing it nearby. Now open the top drawer. Your aim is to organise the underwear, so they are all together. They don't need to be colour-coded or even aligned. Press to rotate them.
Once done correctly, this will unlock:
Now get to unpacking, clicking on the star to finish the level once it appears to unlock:
2012
In the bedroom you start in, open the drawer on the left. On the bottom shelf is a rolled purple tube which is actually a poster. Take it out and put it on the wall (it will fit to the left of the drawer) for another achievement:
There are no other miscellaneous achievements here (and no toilet to flush), so just go ahead and unpack. Click on the star once finished to end the level and unlock:
2013
Start by flushing the toilet for Gotta flush 'em all 4/7.
Go to the kitchen. Start unpacking. You're looking for a microwave and some small fridge magnets. For the microwave, put it up onto the bench, against the wall - if it's in the right spot the time will be displayed. Hover over it and press several times to set the time, which unlocks:
12:00Set the time on the microwave.
Keep unpacking the boxes. You'll eventually unpack several fridge magnets - 1, 2, 3, + and =. Align them on the fridge; you'll need to put them on the side because they won't all fit together on the front.
You need to make the correct equation, 1.e. 1+2=3 for:
Now complete the level by unpacking everything and clicking on the star. You'll unlock:
2015
You need to put all the plants on suitable surfaces for the next achievement. To avoid confusion, do this first before unpacking anything as none are in boxes. You can probably work it out yourself but there may be an element of randomness as to what appears where so the images have been included to give you an idea of what you're looking for.
In the room you start in, there are two larger pots and two long, narrow pots on the boxes.
The bathroom has a single pot that can go up beside the sink.
In the bedroom, there is a single larger pot and two smaller pots on one of the boxes.
The kitchen has another long, narrow pot. You may have to clear some room but put it up on the table.
Now go to the bathroom and flush the toilet for Gotta flush 'em all 5/7.
Go ahead and unpack those boxes. In the bedroom, you will see a pink stuffed pig already unpacked. As you proceed, you'll uncover an orange stuffed tiger. Rotate and place them so they are sitting next to each other.
This will unlock:
Finish unpacking all the boxes and click on the star to continue, which will unlock:
2018
As the final level, you can unlock the Gotta flush 'em all achievement now. Note that there are two bathrooms here, so flush both toilets for # 6/7 & 7/7 to unlock:
If you miss it, you should be able to replay levels - toilets appear in 2004, 2007, 2010, 2013, 2015 and 2018 x 2.
Your last miscellaneous achievement will be unlocked in the babies room with the crib. As you unpack, you'll uncover several toy blocks. Simply make a stack of five high to unlock:
Finish your final round of unpacking and click on the star one last time to complete the game by unlocking:
Congratulations on another quick and easy 100%! 
If you skipped something, the main menu has an "Album Select" option. Choose your save file then scroll through the book to the relevant level. Complete the required action or, optionally, press 
and choose "Start Over' to reset the level and begin unpacking once again.
I hope the guide was helpful. If you have any issues or comments, please head over to the Walkthrough forum.