Feud is a game by Bearwaves Ltd., a UK-registered company.
We collect the following data:
We ask for your email address if you use our account linking feature. It's used to log in to your account from other devices, and for password recovery.
We use this for analytics and to resolve issues. On iOS and Android, we use your device's unique identifier as a fingerprint for login. It isn't tied to your email address unless you link your account; logging out from that device will unlink these data points.
We use PlayFab as our account management backend. You can see their terms here, which contain and link to their privacy information.
We hope this makes sense. Shoot an email to joel[at]bearwaves[dot]com if you have any queries.