> So this is what i've thought; I'm gonna have a Web Based Php Front-end
> for the players to comunicate with the game. And a Ruby Core program
> sinchronized with Cron to be launched every 3 minutes for example. That
> Core will do all these things i can't do from Php, catching MySql files
> that tells it what to do, do it, and update those MySql fields which may
> need updating.

Why not just use PHP for the cron job? It doesn't seem like a good
decision to write the app in two different languages (harder to
develop, harder to maintain, etc).
Also, concurrency is not an issue as long as you use transactions to
enforce integrity at the application level (i.e.: if an attack is about
to occur, damages on both sides (attacker and victim) have to be
updated inside a single transactional block).