Cosmos' Visual Studio Solution file contains over 30 projects. In the main Cosmos.sln file, we use Solution Folder to group related project together. However, in the Express editions of Visual Studio, there's no support for Solution Folders. This means that Express users cant couldn't work on the main Cosmos project. This has now been solved, as there is now a project called CosmosFlatFileUpdater, which makes a Cosmos.Flat.sln file, which contains the exact same projects as the main Cosmos.sln file.