I liked the facebook sign in option in games like HayDay where even strangers could visit your farm, buy things and even add you as a friend.

For vaults we could do the same and later on be able to set up a maket where you can trade equipment others can buy or resources.

So hackers can get my FB username and password from hacking this site. No thanks.

Facebook have a similar verification system as Google, if hackers can get access to your Facebook then it's more than likely they can get access to your Google email as well with two step verification.

It is easy to protect yourself with phone and browser verification.

However nothing is safe from stupidity and phishing, even if they aquire your password through phishing they still have to get through the 2 step verification and that is still only possible if they gain access to your browser or phone.

Facebook are known for many things including leaking personal information and credentials exactly like Google, lack of security is not one of them.

Seriously no not everything needs Facebook.......not everything needs to connect to Facebook.....

This is a single player game with no online interactions besides purchase transactions.

It's not built for visiting anyone else's vault.

Supporting features like that require a lot of forethought unless you want to introduce a lot of bugs.

Unless they were already thinking in that direction and designed the system to be able to deal with atomic action disruptions and simultaneous transactions I'd rather not see the plethora of ways an app can crash thank you very much.

Actually one of the facts I love about this game is the fact it's not linked to facebook forcing you to like it or invite your friends to get more stuff or get ahead in the game. Let's leave that alone hey?