If your game uses adobe flash engine (most facebook games are), I believe you are out of luck. This is not Firefox's fault as flash is blocked on iOS platform. Every browser on iOS will never be able to play flash games.

If I understand correctly, Candycrush is available as a separate app in the app store, not in any browser on the iphone.

Chris Ilias said

If I understand correctly, Candycrush is available as a separate app in the app store, not in any browser on the iphone.

It is available on browser using flash (as a facebook game). I've been playing it several years ago.