scriptcs supports REPL which is an acronym for Read–Eval–Print Loop. The scriptcs REPL allows you to quickly try out and experiment with C# code without the need of a script file or IDE.

The REPL uses the context of the directory it's executed in, so you automatically have access to all installed packages.

You can also (just like in script files) use the #load and #r directives to reference CSX files and assemblies.

The scriptcs REPL can be started by running scriptcs without any parameters.
To exit, press CTRL+C at any time.

To reference other assemblies, you can use the #r directive.

C:\>scriptcs
scriptcs (ctrl-c to exit or :help for help)

> #r "MyAssembly.dll" 

The scriptcs runtime will first try to resolve and load the assembly from the bin folder, and if that fails, try loading it from the GAC.

To reference other script files, you can use the #load directive. The path provided can be either absolute or relative.

C:\>scriptcs
scriptcs (ctrl-c to exit or :help for help)

> #load "MyFile.csx"
> #load "C:/MyFile.csx"

In the example below, we install the Newtonsoft.Json NuGet package and use it inside the scriptcs REPL.

C:\>scriptcs -install Newtonsoft.Json
INFO : Installing packages...
Installing packages...
Installed: Newtonsoft.Json
Package installation succeeded.
Saving packages in scriptcs_packages.config...
Creating scriptcs_packages.config...
Added Newtonsoft.Json (v6.0.8, .NET 4.5) to scriptcs_packages.config
Successfully updated scriptcs_packages.config.

C:\>scriptcs
scriptcs (ctrl-c to exit or :help for help)

> using Newtonsoft.Json;
> JsonConvert.SerializeObject(DateTime.Now);
"2013-05-22T12:50:47.2474102+02:00"