Stop Any Notification/Game Request in 3 Seconds on Facebook

When you receive an invitation to play Candy Crush, simply hover your cursor over the Facebook notification box and look to the right of the Candy Crush icon. You’ll notice a small circle to mark the notification as “read,” and a little “x” that will say “Turn Off …” when you hover over it.
Example (Candy Crush):
The next time you receive an invitation to play Candy Crush, simply hover your cursor over the Facebook notification box and look to the right of the Candy Crush icon. You’ll notice a small circle to mark the notification as “read,” and a little “x” that will say “Turn Off …” when you hover over it.
Click the X, and you’ll be asked if you want to “Turn off notifications from Candy Crush Saga.” Click “Turn Off” and you will be greeted with a message letting you know that you will not get notifications about Candy Crush.