The concept is rather simple:
We all start with the same amount of cash. With that cash, you can buy barrels. You can buy or sell barrels at the price of the day. Everyday we update the price at the same time (eg 1pm GMT) and it remains the same for the rest of the day untill next update.
We take prices from this webside:
http://www.bloomberg.com/energy/
the price per b for Nymex Crude Future
eg: I have 200$cash and the daily price is 100$/barrel. I can choose to buy 1 or 2 barrels, or none and keep my money. If I buy 2 barrels, I can choose to sell them, or one of them, next day at the price of that day(preferably higher). The trick is to know when to buy or sell. I.o.w. when prices will raise or fall. If prices will raise you buy to sell later at a higher price.
after a few weeks we stop and whoever has most cash wins.
A full and structure explenation comes later if there are people willing to play the game.