gambas
A very active open-source project as of 2023, whose name is a recursive acronym for "Gambas Almost Means BASIC". It is pretty BASICy though, in spite of some strong Java scents (even though it is written in C++).
Gambas is a modern 21st-century BASIC with many features and extensions for all kind of desktop/server applications development. It certainly is not more talked about because it remains a Linux-only platform since it was released. Its website shows an above-average documentation quality.