Pharo, Pixie, Pony, ...?
https://pharo.org/ - A language with an IDE
http://pixielang.org/ - A lisp.
Sadly not a match. All I remember was that the language was written in C, compiled to bytecode and was executed in a virtual machine (like Lua, and similar languages). It was "small" and "fast" and probably had a C-like syntax.
I should perform a decent search, because the more I think about it the more I'm annoyed now!
I should just post an "Ask HN: Tell me of your niche languages" and hope I get lucky!