Hello! You only need to provide an email address and create a password in order to create an account. We're cross platform so the Mirrorscape account links your account across all devices.

Do we need Mirrorscape account for singleplayer ?

Yes, to access your account, save your maps, sync your heroforge account etc... you will need to create a mirrorscape account. You can use a throwaway email address if you don't want to use your main one for personal reasons :)