Wikipedia
SharpOS (operating system)
SharpOS was an open source .NET- C# based operating system that was developed by a group of volunteers and presided over by a team of six project administrators (Mircea-Cristian Racasan, Bruce Markham, Johann MacDonagh, Sander van Rossen, Jae Hyun and William Lahti). It is no longer in active development, and resources have been moved to the MOSA project. This operating system is only one of three C# based operating systems released under an open source license. SharpOS has only one public version available and a basic command line interface.