I'm not an expert but agree with Informatix.
The way I would face it is, regardless of the technology used, to have a well defined schema of what is involved in your game: which is the amount and nature of data to be kept on the server, how is the game flow, and which are the basic interactions needed for it to work, even the ones related to game start, game end, abandon...everything. What's more, I would even start with a simple tic-tac-toe, which may seem obvious, but it can help to do the exercise. Once you have everything, decide if you need DB or can do it with simple files, if you want to use PHP and MySQL or do some other kind of protocol, existing services, etc.