Retro Forth and Factor are both neat. There's a commercial Forth (8th) that has a free hobby license and very affordable professional licenses that I've been pl

Retro Forth and Factor are both neat. There's a commercial Forth (8th) that has a free hobby license and very affordable professional licenses that I've been playing with lately and having fun. It has a small, yet active community. The language itself is pretty full-featured for a Forth too with a GUI, cross-compilation to native executables on Windows/Mac/Linux/iOS/Android, lots of database access...etc. It is not open source sadly.