Betterium is an interpreter + runtime for the Hassium programming language.
It's written in C# and is very well optimized.

Hassium is a programming language written in C# for the heck of it.
It is intended to be easy-to-write and easy-to-learn.

A simple Hello World program in Hassium:

print ("Hello, World!");

For documentation, take a look at the original Hassium interpreter:
Hassium