How players login their existing wallets?

[sweatyc]

Thanks for the great demo and ready-to-use plugin, it helps a lot on understanding Ethereum with Unity.

The plugin can now create wallet and save it as a local data file for later use, but what is the best way to let players to login their existing wallets securely? Few solutions I can think of:

1. Login through MetaMask (MetaMask doesn't have a native Unity plugin, so may be a web interface popup for login? This can be hard and require well understanding on how data pass around)
2. Simple let players to input the private key string, or select private key file.
3. My own (centralized) server that players can create accounts and login with usernames and passwords. The wallet private keys are saved on database with their accounts. (Just like MetaMask but only for my game)

It's because, for example in mobile, you don't want a player to create new wallet every time he use a new devices, and he can play on a same game progress in multiply devices.