One of my all time great hobbies is designing and implementing programming languages, I have been doing this for over 20 years now. I wrote my first compiler on the C16, followed by several more on the Amiga, most well known of which is Amiga E, and suprisingly, my False Language.

For my Masters and PhD respectively, I embarked on 2 language projects, first the Bla Language (around the concept of first class environments) and the Aardappel Language which is about graphical tree rewriting and distributed computing.

WadC editor: A programming language / procedural map editor for Doom 1 & 2

I created the SHEEP Language for Amiga Inc, which was intended to be the central system scripting language, and CryScript for CryTek.

I created MANY smaller language designs, most not actually implemented, you can find a neat list of all my crazy ideas here: Language Design Overview.

Currently I am working on a game programming language (& engine) called Lobster and still trying to figure out what to do with my automatic refactor system, Restructor