Since this is dealing with sensitive account information, can you please send in an account help request for me? You can use this account and the associated email address when filling out the help request.
Please include the following information as it'll help me figure out what may have happened,
The account name that you selected when you signed up using Facebook originally
The email address for your Facebook account
Which browser and OS are you using,
A link to a screen capture showing the error you get when you attempt to sign into the account.
Is Armor Games listed under your Apps still? Or was this something that was removed recently? To verify you can see all of the Apps that you have approved to use Facebook with here - https://www.facebook.com/settings?tab=applications