Throughout the game you will find small black data cards weighing about 0.10lb each. There are around 150 of these different data items, and with every 10 that you decode you complete a goal and gain a skill point. This makes them desirable, but they can also be very annoying to find and decode.

This guide was originally going to list all 150 data items and their corresponding codes, but it has been discovered that the game randomly assigns a different code to each data item. For example: in my game the code for data item #139 might be Thursday, but for someone else, Thursday will be the code for their data item #56. (Thank you to RubenFox for discovering this and commenting!) No two games will be the same.

This guide does not list all of the different locations of the data items. It was written to provide information on the codes. The majority of the data items will always be found in the same places, but there are many that can only be found in random encounters on the world map. To find them, you will simply have to thoroughly play the game.

When you find all 150 data items, you will still continue to find more on corpses or in computers, but upon bringing them back to the shelter they will be catalogued as 'corrupt'. You can only ever find 150 data items, these corrupt ones cannot be used, so once you find all 150, you no longer have to keep collecting them.

This means that even if you miss a laptop or a smart phone in an obscure location, there are more than 150 data items in total to be found. Just keep looking and you are sure to find all the data items you need to complete the achievement. (Thanks to ExHippy for discovering this!)

In order to be able to start hacking these data items, you will need Doug to set up the computer system for you in the library. A few days after he wakes up there should be a short cutscene with him proposing the creation of the system to you. Just make sure he doesn't die and you should be fine.

Each data item will list randomly the letters that make up the password, and give you a few of them in order for free.
For example:

Random Letters Given: siptoi
Letter Locations Given: _ _ l _ _ _ c _

Just start moving the letters around in your head to try and make the word. To make it easier, use a pen and a piece of paper, or just keep entering different combinations into the data system. If you are really stuck you can always use a website like * http://wordunscrambler.com/ * to help you out.

Oh, and if you haven't figured it out yet, the above word is politics.

Soon you will find data items that are no longer unlocked exclusively by letter based passwords. Now, to crack the code you will have to incorporate numbers into the password, to form words in 'leet-speak'. This is sort of internet language in which letters are replaced by numbers, for example, 'leet-speak' would be 1337-5p34k (1337-5634|< if you are really hardcore).

Thankfully only certain letter/number combinations are used, they don't go through the entire alphabet.

From what I have seen so far these are what the passwords will use:

a = 4
e = 3
i = 1
o = 0
g = 6
b = 8
t = 7

Passwords here will be a mixture of letters and numbers, as well as passwords made up of all numbers. These passcodes are usually very short.
Here are the examples:

Random Letters Given: 1 r 4
Letter Locations Given: h _ _ _

Random Letters Given: 6 0 5 0
Letter Locations Given: _ _ _ _ 3

These can be easy if you remember what the letters convert into. The first is h14r (hair) and the second is 60053 (goose). Just change the numbers to letters, figure out the word, and change the numbers back again.

Here are some codes I have found so far to help people out:
_ _ _ 3 = 5h03 = shoe.
_ _ _ _ 5 = 80085 = boobs.
_ 3 _ _ _ _ = 33r13 = eerie.
_ o _ _ = mov3 = move.
w _ _ _ - w41l - wail.
_ _ _ 7 = h347 = heat.
_ 3 _ _ _ = 8345t = beast.
_ _ y _ = t0y5 = toys.
_ _ _ d = 600d = good.
_ _ _ _ 5 = 84515 = basis.
_ _ 4 _ _ = 6l455 = glass.
8 _ _ _ _ = 800t5 = boots.
_ 1 _ _ = h155 = hiss.
m _ _ _ = m1nt = mint.
_ _ _ l = 74ll = tall.
c _ _ _ = c4t5 = cats.
_ _ u _ = 5oup = soup.
_ _ _ l = 83ll = bell.
_ _ n _ = 50ng = song.
t _ _ _ = t3nt = tent.

Make sure you don't mix up your l with 1 and your o with 0 while in-game, they look very similar. If you think you know the word for sure, but it doesn't seem to be working, it just may be you have the wrong letter/number look alike.

As you progress further into the game, some data items will not give you the letters to help you out.
They will look something like this:

Random Letters Given: ?????
Letter Locations Given: d _ _ _ s _ _ r

These can be a little more difficult, but if you cannot figure them out you can always use a website like * http://www.morewords.com/ * to figure it out. (Thank you to mkent41616 for commenting about the website!)

If you haven't figured it out the above word is dinosaur.

After a while the passcodes will contain a mix of all three difficulties. You will have to deal with letters, numbers, and not being given letter clues.

It will look something like this:

Random Letters Given: ???
Letter Locations Given: _ _ 1 5 _ 3 y

Thankfuly you do not need to answer this with any more numbers, they only look for letters. To solve this, you will have to convert the numbers into letters. So 1 becomes i, 5 becomes s, and 3 becomes e. (Remember the chart above!) So you then have:

_ _ i s _ e y

Because they don't give you any hints after this it is up to you to find out what fills in the blanks. In this case the letters are w, h, and k, in that order. This gives us whiskey.

Remember though, once you think you have figured out what the word is you have to submit it with the original letters turned back into numbers, or it will not work. So wh15k3y is what you will then need to re-submit in order to get the password correct.

As you move outwards in a circle from the shelter and Splendid, the passcodes will become longer and more complex, changing from things like shop, to shopping, or friend, to friendly. Eventually they will start to contain up to two words together, such as bluebird, or mailbox.

I hope this guide helps! Good hunting!

Alright, now that the game has been out for quite some time, a complete (to my knowledge) list of the words has been made. Here they are for you:

Four letter words:

50ng
mov3
83ll
h155
c4t5
600d
5h03
t3nt
5oup
t0y5
h41r
74ll
m1nt
h347
w41l

Five letter words:

horse
irony
squid
queen
6r34t
60053
slime
bride
fleet
peach
33r13
tiger
songs
otter
chain
8345t
money
toast
6l455
timer
6h05t
heart
slate
beach
viral
panic
booze
death
rainy
800t5
80085
84515
apple
shark
groan
flier
power
groom

Six letter words:

savage
hunger
wooden
goofed
shovel
doctor
arrows
sorrow
caring
moving
ravens
heroes
beaver
sonnet
dragon
knight
fallen
invade
button
animal
hammer
wonder
soccer
robots
insane

Seven letter words:

violent
happy
cartoon
receipt
thunder
history
sailing
shotgun
reaches
release
airship
chicken
sparrow
january
bottled
mailbox
because
wh15k3y
curious
vampire
partial
culture
popcorn
modeled
monster
written
515t3r5
killing
basterd (replace the e with an a, Steam censors the word otherwise)
boating
candied
nuclear
weekend
raining

Eight letter words:

sandwich
wordplay
quandary
tortoise
chestnut
m34t84ll
tomatoes
shopping
hesitant
dinosaur
3l3ph4nt
friendly
sanitize
password
computer
question
baseball
thursday
insisted
bluebird
folderol
babbling
politics
advanced
february
bookmark

Nine letter words:

heartless
heartache
houseboat
spaghetti
videogame
submarine
broadcast
microcosm
character
xylophone

Ten letter words:

television
4p0c4lyp53
artificial

A big thank you to Solosochi for providing this list, and Armageddon for making corrections!