For a limited time (Til mid Dec) Ubisoft is offering "Assassin's creed 3" which is a assassin's creed set in the revolutionary war for free however you need to download their uplay store program to run the game.



Download link = https://club.ubisoft.com/en-US/ubi30

For more info

http://store.steampowered.com/app/208480/

http://assassinscreed.ubi.com/en-US/games/assassins-creed-3.aspx