Here’s a video of an ink- and pen-based, multi-player game called Euclidean Crisis.
“The game was developed by Daniel Salinas, John Shedletsky, Travis Skare, and Doug Wilson over ten weeks in spring 2006 for Stanford’s CS1934 class.”
The video says the program was written in C# using the Tablet PC SDK and speech API.
You can download the game from the group’s website. I haven’t tried it yet. Anyone else have?