The project has been migrated to GitHub from CodePlex: CS-Script.
CS-Script is a CLR (Common Language Runtime) based scripting system which uses ECMA-compliant C# as a programming language.
CS-Script is one of the most mature C# scripting solutions. It became publicly available in 2004, two years after the first release of .NET. CS-Script supports both hosted and standalone execution model. It allows seamlessly switching underlying compiling technology without affecting the code base. Currently supported compilers are Mono, Roslyn and CodeDOM. It offers comprehensive integration with most common development tools: Visual Studio, VSCode, Sublime Text 3, Notepad++. It can be run on Win, Linux and Mac. And it is compatible with .NET, Mono and .NET Core (ongoing development).
Over the long history of CS-Script it has been downloaded through Notepad++ plugin manager alone over 
For the all CS-Script details go to the project Documentation Wiki.
Ubuntu package: latest version