Crayon Physics is one of a series of monthly, deadline-driven game development exercises by Finnish game developer Petri Purho. Purho releases a new game every month which can be downloaded and played on PCs running Windows.
If you don't run Windows or would prefer to watch a spoiler video to remove the possibility of getting addicted to game you don't have time to play, here it is:
I find it particularly interesting that the platform Purho uses allows fans to creating their own levels for the game, which Purho then shares with other readers. They can even stray from the game's look and feel, and often crib from other game designs in their own development.
To learn more about rapid game development, visit the Ad Lib Game Development Society's home page. Their site includes a great list of strategies and tips that can be applied to many other team-based creative activities.