A Lisp interpreter polyglot (in Malbolge20 and Malbolge Unshackled; often dubbed the hardest programming languages in existence). Currently supports the following features:

• basic mathematical operations on natural numbers eq, +, -, *, /, %
• list operations: car cdr cons quote atom
• callables: define defun lambda if print

Minimum of 2 gigabytes of RAM is required. It's recommended to use a fixed-width interpreter.