Io was fantastic as a personal learning vehicle, over ten years ago. I did have a game project that used it, right in the lull where Lua’s FFI was still a little rough and JS did not quite break out of the browser.

Its simplicity also made it great to write an interpreter for, including GC. However, nowadays the focus shifted to JIT, mostly via LLVM, which leaves such free-form languages unable to compete on performance, without significant effort.

I do fondly remember the endless explorative chats with Steve Dekorte and the other language geeks on IRC!