The most aborbing software that MS has ever developed, well... for me, is mine sweep. It is a pity that I had never played it again since I moved away from winxp. So I wrote one for myself.
Server implementation of the mine sweep web application. It now provides services such as user signup/login, records creation/querying via web APIs.
The front-end code are developed and maintained in another project mine-sweep, and is imported as a submodule of this repository.
The application is deployed on heroku. To play with the live version, please visit http://mine-sweep-1008.herokuapp.com.