It might be too soon to call it abandoned, but I was very intrigued by the Austral [1] language. The spec [2] is worth reading, it has an unusual clarity of thought and originality, and I was hoping that it would find some traction. Unfortunately it seems that the author is no longer actively working on it.
[1] https://austral-lang.org/ [2] https://austral-lang.org/spec/spec.html