Mike Heydlauf (also known as Mike Walters) has created an awesome WPF physics game called Chicken Coop.  It reminds me a bit of ChuChu Rocket, but with physics and no cats.  It includes great tutorials; I challenge you to not get hooked! smile_nerd  Some details from ChiefChicken himself:

Chicken Coop is a physics-based puzzle game developed using the Newton Dynamics physics engine. Chicken Coop was written in C# using .Net 3.0 and WPF (WCF for back-end services and level publishing). Inspired by the classic puzzle game Lemmings, I decided to write Chicken Coop because I wanted a Lemmings-style game that shipped with a level editor, and because I wanted a good excuse to learn WPF.  I know WPF isn’t necessarily targeted for game development, but it really lets you do some powerful things easily (for example: checkout how the level selection buttons are actually “live” levels when you hover over them). 

Be sure to start with the tutorial levels to get a feel for the game before diving into some of the more difficult levels.  I would also encourage players to experiment with the level editor and publish some puzzles of their own design.  I hope you enjoy playing the game as much as I have enjoyed creating it.

Thanks,

Mike Heydlauf (ChiefChicken)