All three of these games are free right now.

HumbleBundle (Steam): https://www.humblebundle.com/store/layers-of-fear-and-soundtrack
GOG: https://www.gog.com/game/oxenfree
Steam: http://store.steampowered.com/app/368230/Kingdom_Classic/

Also, Watch Dogs, Assassin's Creed IV: Black Flag, and World in Conflict: Complete Edition are free right now on the Uplay app.

Uplay: https://freetrial.ubisoft.com/

This is the page to go to to keep up with what's presently temporarily free. https://www.reddit.com/r/Freegamestuff/

You can also check the front tabs at http://www.g4g.it/