Best Client/server Architecture For A Mobile Management Game?

Best Client/server Architecture For A Mobile Management Game?

For the past year I have worked on a small company that develops a traditional browser based strategy game, of the likes of Travian or Ogame, but using a more interactive approach like Tribal Wars 2.

The game is made in a simple php server without frameworks and a simple mysql database, and all of the game happens in a single static page that is changed through ajax calls and has a map made in pixi.js. The automatic updates are delivered to the client side through polling the server which then queries some specific database tables made for the purpose for changes.

While this approach is solid and works, it has 2 big problems:

• Having a mobile app is increasingly more important and there are not enough resources for having two separate codebases. Having a app which is simply a wrapped webview is also not a solution because the performance of a really complex page with a giant webgl map is, while usable, really subpar;
• Polling the server for changes creates a lot of programing challanges that make some simple tasks really complicated and creates a lot of convoluted code if we dont want to hurt the game performance, as we are not going make dozens of database queries every 5 seconds.

I want to start developing a game idea that I have that is basically inserted in the same genre and which is going to be, at least initially, mobile only. The real problem here is that after reading a lot on the internet, I am confused on what should be a good client/server architecture for me to start prototyping in a way that I do not run in the problems mentioned above.

Basically, above all, I want the server to be able to know which page/screen/state is each client looking at, and be able to send them messages when another client changes something on that specific screen. It would also be nice if the solution is something lightweight on the server side to be able to scale a little.

Client side I was thinking about Unity because of being cross platform, of all the environment around it (ads, analytics, a lot of support and answers on the internet), and because I have previous development experience with it.

Server side is the real question.

• Simple http calls will not work and so PHP is out of the equation.
• I have though about using node.js with socket.io to use websockets solving the polling problem. Is this a good idea? Would it be better to store the game state in a relational or nosql database in this case? Would this work on unstable mobile conections?
• Lots of people seem to use a c# and sockets for unity. Would this be overkill in this situation? Taking this approach how would the data be stored? would it be feasible with a linux server or would I need a windows server? Would this work on unstable mobile conections?
• Don't know, I'm open to suggestions.

tl:dr: I want to make a mobile management game in unity but am confused what to choose for the server side architecture considering that I want the server to be ablose to send a message to the client without the client asking for it. Is there anything I should take in account?

Sorry for the broad question and thanks for the help.