You can claim it here:
http://www.overkillsoftware.com/kentokeys/

1. Login to the website using Steam acount
2. The key will be revealed after you login :)

You can claim it here:
https://www.humblebundle.com/store/layers-of-fear-and-soundtrack

1. Login to Humble Bundle account
2. Go to the link and add the game to the cart
3. Redeem it and check your email
4. Reveal the key and redeem it on Steam :)

http://store.steampowered.com/app/391720/Layers_of_Fear/

http://store.steampowered.com/app/550210/Layers_of_Fear__Soundtrack/

You can claim it here:
https://www.ubisoft.com/en-gb/event/happy-playdays-2017/

1. login to your ubisoft account
2. go to the link and claim all the game
3. and play it :)

FYI: all of the game will be expired to claimed until December 23th, 2017

http://store.steampowered.com/app/242050/Assassins_Creed_IV_Black_Flag/

http://store.steampowered.com/app/243470/Watch_Dogs/

Free random Steam Key after completing quests on bananatic[www.bananatic.eu]

You can claim it here:

https://deals.razerzone.com/blog/giveaway-memoria-christmas-10000-keys-grabs/

1. login if you didn't do it
2. after that, you got a task to login in razerzone website
3. login on razerzone website and the website will be redirecting you to your original giveaway link
4. click continue and the key will be revealed :)

http://store.steampowered.com/app/243200/Memoria/