When I worked at Google, I made an App Engine Flexible runtime for the Whitespace language (only valid characters are space, tab, etc). https://en.wikipedia.org/wiki/Whitespace_(programming_langua...

App Engine Flexible was another one of these products that just needed a container that responded on certain ports, it was quite fun to get it working. But I ended up writing a tiny "compiler" that would compile a small subset of Python to whitespace since writing just whitespace itself was quite challenging, obviously.

I wanted to release it on April Fools Day but my manager was totally against it because April fools had become its own serious entity in the marketing org and he didn't want me stealing their thunder ( these days Google has dropped April Fools jokes altogether, I guess it got a little played out).