Hi guys, I need some advice. Let's say I want to make a multiplayer live chess game that has an ELO rating system. I know I have to connect a data base to my game that receives an unique ID and stores a rating, but how am I supposed to make a live 1v1 interaction? And one more thing, I want both players to see their pieces in the bottom of the screen. I work in unity and I didn't find a relevant tutorial to what I am trying to do, almost all of them are about fps/rpg multiplayer.

I would greatly appreciate if you can add to your answer an additional link to a tutorial ( if you know one ) about databases connected to unity. Thank you.

Just asking the question makes it obvious you are new to network programming and possible programming in general, but don't let that discourage you.

There are 2 ways you can go about this:

1. Use a networking engine such as raknet (http://www.jenkinssoftware.com/features.html), this will allow you to get up to speed with a working solution as fast as possible.
2. Learn low level network programming from scratch by following a guide such as Beej's guide to networking (http://beej.us/guide/bgnet/). This will take long time until you get a working solution but you get a good understanding about networking programming.

If you want to be good at networking programming, you have to learn the low level details at some point.