Romans: Age of Caesar's

Romans: Age of Caesar is an upcoming co-operative city building game from FireFly Studios, who you may know as the folks behind the Stronghold series. It's currently being alpha tested but is expected to launch for iOS and Android sometime in 2021, with a PC open beta expected before the end of the year.
FireFly has described Romans: Age of Caesar as being a spiritual successor to the Caesar series, with some of the people involved in that franchise now working on this title. It will use a similar art style to those games as well as gameplay mechanics that nod towards them too, for a dash of nostalgia but there will also be a grand strategy layer added on top.