Gemsnake

Are you coding in C#, but want the flexibility of Ruby or the libraries of Python? Gemsnake lets you have all three from the comfort of C#, without needing to install Python or Ruby.

The best part is it's as easy as:

RubyEvaluator Ruby = new();
Ruby.Evaluate("puts('Hello from Ruby!')");

PythonEvaluator Python = new();
Python.Evaluate("print('Hello from Python!')");

Gemsnake also lets you return values:

string Greeting = Ruby.Evaluate("return 'Hi!'").ReturnValue;

You can also run code asynchronously:

await Python.EvaluateAsync("print('running in the background')");

Setup for Visual Studio

Download Gemsnake.zip from the latest release.
Extract the zip and move Evaluator.cs, RubyEvaluator.cs and PythonEvaluator.cs into your project files.
Move RubyEvaluator.exe and PythonEvaluator.exe into your binary output folder.

Setup for Unity

Download Gemsnake.zip from the latest release.
Extract the zip and move Evaluator.cs, RubyEvaluator.cs and PythonEvaluator.cs into your Assets folder.
Create a folder called StreamingAssets inside in your Assets folder and move RubyEvaluator.exe and PythonEvaluator.exe into it.
Install the Newtonsoft.Json package via the Package Manager (add package by name -> com.unity.nuget.newtonsoft-json). (Help)
Comment out (add "// " before) the first line of Evaluator.cs, as Unity doesn't support dynamic data types.
Create a script that looks like this:

using UnityEngine;
using Gemsnake;

public class NewBehaviourScript : MonoBehaviour
{
    RubyEvaluator Ruby;

    void Start() {
        RunCodeInRuby();
    }

    async void RunCodeInRuby() {
        Ruby = new RubyEvaluator(RubyExecutablePath: Application.streamingAssetsPath + "/RubyEvaluator.exe");
        object Result = (await Ruby.EvaluateAsync("return 2 + 3")).ReturnValue;
        Debug.Log(Result.ToString());
    }

    void OnApplicationQuit() {
        Ruby.Stop();
    }
}

Playtest your game, and after a few seconds, 5 should be printed to the console.

Notes:

Make sure to use EvaluateAsync rather than Evaluate, as otherwise Unity will freeze.
If you don't stop the evaluator on OnApplicationQuit, it will continue running in the background after the playtest ends.

Using gems/packages

If you want to use gems/packages, or upgrade the language version:

Download Gemsnake Build Tools.zip and run the build scripts.
Input which gems/packages to include and new executables will be built.

Objectives

Gemsnake is designed as a replacement for IronRuby and IronPython, which have been long discontinued.
It's designed to help you run Ruby & Python code while creating an interface in C#.
It targets .NET 7.0.

How it works

Gemsnake works by creating an executable ahead of time using Ocran and PyInstaller for Ruby and Python respectively.
These executables can run code from a string using Ruby's eval() and Python's exec(). As Python's exec() does not return a value, the code input is wrapped into a function and called.
The C# program will start these executables as processes running in the background. They communicate over a localhost TCP connection, and you can specify over which port if you desire.

Limitations

As PyInstaller and Ocran create executables, this will only work on Windows. (If you run Build PythonEvaluator.py from Linux or macOS, you may be able to get Python to work on those platforms.)
The bigger the executables are, the longer they take to start (only really an issue if you are using custom gems/packages).
Two applications running on the same ports on the same computer will conflict with each other.