A kind of "pure" PicoLisp (not "pure Lisp"!).
https://software-lab.de/down.html
For something even smaller, download miniPicoLisp.tgz. It is a minimal version, without support for databases, UTF-8, bignums, IPC, networking and other system-dependent functions. A kind of "pure" PicoLisp (not "pure Lisp"!). It supports the full PicoLisp language, but runs faster, and uses even less memory space. It should also not be restricted to Unix. In addition, it compiles and runs also on 64-bit systems.
Jon Kleiser wrote an OpenGL library (native in the 64-bit version, or separate at gl.tgz for the 32-bit version), and a Chinese Checkers program running on top of it.
Some philosophical and practical aspects are discussed in "A Radical Approach to Application Development (PDF)", and a description of PicoLisp DB and GUI Development principles is in "A Unifying Language for Database And User Interface Development".
Please enjoy :-)