The goal of the Ludum Dare competition is to make a simple game in 48 (or 72) hours. I believe the organizers run the competition about three times per year - and the prize money is nothing more than the honor. This was the third time I participated in the competition, you can read about the other times here: Max Manus, and Battle of Khe Sanh.
As you don't make any money from the competition, the idea is that you should learn something and/or maybe test an idea you have that you may sell as a complete game in the future. You will also get feedback on the game from other participants in the competition. What I learned this time was to not update any software before the competition. I updated Unity to a new version and realized that some of the old features had been replaced with new, so it took a while from the actual game design to learn these new features. While making the game, I also found a few other ideas I will try to test in a near future.
One of the things I learned from the last competition was that a theme from a real war is not a good idea, especially not the Vietnam war if you are going to market your game in the US. So in this competition I decided to make a game where you kill, but you are killing your "bad thoughts," thus the name "Kill your thoughts." This is the description:
You are participating in a competition where you are making a game in 48 hours. If you are participating in such a competition you have to be able to fight thoughts like visiting Twitter, or drink beer, and feelings like "My cat makes better games than me!" To help you fight these feelings, your mind is actually using an armored Saab on the top of your screen.
...and this was the result (You can test it here):