I took a look at their web page. It looks like they have a bank of virtual machines for rent. So basically you are logging on to a remote computer, and playing the game from that remote computer. You don't have to have the hardware to run the game, the remote computer is actually doing all the work. Your computer is just a terminal. As long as you have a good terminal and a fast enough connection, the remote machine does all the heavy lifting.
Or, at least, that's what I got from ready the information on their web page. This could be good for someone who can't afford to buy a new computer to run the game, you can rent one much cheaper.
