Big Fish Games is giving away some FREE games if you sign up for their newsletter. After you sign up for the email list, they’ll email you codes to get your free games. You could probably remove yourself from the email list right after you get the codes. I have no idea if it’s just for the PC versions or not.
These are all casual games.
From this link you can get the following games free:
From this link you can get these games for free: