title: Timed server events with ruby on rails
body: <p>I am attempting to create a web-based game in Ruby on Rails.  I have a model named 'Game', which has a datetime in the database entry that corresponds to a time that I would like the server to call the Game model's update_game function.  Depending on the game's settings, this could be every 30 seconds to every 12 hours.  </p>
  
  <p>Ruby on Rails only seems to work when it receives an HTTP request; is there a slick way to get my game to update on a periodic basis independent of HTTP requests?</p>