I did not find gforth or factor to be very easy to get up and running with. If you want to learn forth concepts, you can build one yourself easily in any langu

I did not find gforth or factor to be very easy to get up and running with. If you want to learn forth concepts, you can build one yourself easily in any language (lots of examples), but Assembly or C are the most idiomatic as they allow you to get to a much lower level. Every forth system is different, but they share a lot of design fundamentals. There are almost too many to count. If you're okay with closed source, 8th has a very nice free version if you just want to get a hang of writing forth code in it. I usually recommend that one check out 8th as it comes with all the niceties of modern scripting languages and can cross-compile to a lot of systems, has GUI support, bluetooth, iPhone/Android, modern data structures, database support...etc. It's also a bit confusing that most Forth systems were traditionally for embedded work. There are a few commercial offerings (SwiftForth and VxForth) for that. It used to also be extremely common to bootstrap new hardware with Forth as you got a full REPL so you could interactively interact with the hardware and test out each piece before a compiler like C could be ported to the system. I'm not sure how common that is now, but there are a lot of Forth systems that are pretty barebones compared to modern languages. You have to look around.