The login stalls out at about 50% on all browsers and facebook's Gameroom. This has been going on for at least 9 hours now. I don't see any mention on Facebook's page for Dragon City nor anywhere here.

Have cleared the cache, rebooted, tried different IP addresses, different PCs, etc. Filing a support request will mean that tech will look at this issue in about 10 days, which is useless for all time sensitive games, like the Heroic Race.

Perhaps the Facebook server is down, while you wait for it to be resolved you can play on a mobile device or use an android emulator on your pc. Or the Windows version, which is the best option for the pc.