Microsoft's weekly online challenge where US-based holders of a Windows Azure account (including a 90-day free trial) can win prizes is running again with three weeks still to go.

As with earlier versions of the game, participants code a player ‘bot’ that that will compete in an online game of Rock, Paper, Scissors – with some additional embellishments. The bots are hosted on Windows Azure and  take part in battles with every other other competing bot. A bot that wins a game scores 3 points on the leaderboard and a tie scores 1 point. The number of points you can receive depends on the number of players.

The game is both a sweepstake and a contest. Each Friday until the end of the contest on January 25th 5 bots will be selected as winners of a $50 Best Buy Gift Card, regardless of how they perform. In addition each week the top 10 performing bots according to the leaderboard get entered into the Grand Prize Sweepstake which will be drawn on Friday January 25. Three randomly selected winners will win the following prizes:

• First Prize. A 32G Microsoft Surface with Windows RT
• Second Prize. A Xbox 360 4GB with Kinect Bundle
• Third Prize. $150.00 Best Buy Gift Card

As with its previous versions, the concept of this game is to build a bot that will compete in an online game of Rock, Paper, Scissors – with a few additional rules.  participants code a player ‘bot’, host it on Windows Azure, and its take part in battles with other competitors.

You don't have to be in the US to play the game and as a challenge in AI or applied statistics it is probably interesting enough to attract entries even among those inelible for prizes. Do be aware however that deploying the Bot Lab will incur charges if you're not using one of the free Azure account offers. If you are using a trial offer, hosted time will consume "compute hours" from your free allotment. Therefore, be sure to 'turn off' your Bot Lab when you're finished.