Game Maker community SigmaNine.net are holding their first contest. Development time is limited to 24-hours however you have until 11:59 GMT on January 25th to submit your final game which means that work can be split over the week. You are required to keep a log of the time spent on your game for submission with your entry.
The theme requires that entries are set on Earth at any point in the past. Full details on how to submit your game and details of the time restrictions can be found here.
There are no cash prizes but a “virtual cookie”(??) along with a front page feature on the site and review by NAL will go to the winner.