Comment by livrem

I have learned it (somewhat) by playing around in TIC-80 and Löve2D (including LoveDOS).

Both Lua and Fennel are tiny languages. You can skim all the documentation in a short evening. Fennel does not even have its own standard library, so keep the Lua documentation close at hand.

I appreciate the simplicity of both Lua and Fennel. There are some ugly parts, but all languages have those.

Janet (later project by Fennel's creator) is a nicer language that is also portable and embeddable, and has a nice standard library, but Fennel runs anywhere Lua runs. Janet is great just on its own for scripting and not sure I would want to use Fennel for that anywhere Janet is available. But as a way to script games in e.g. Löve2D it seems like an excellent choice.