It's simple in practice to learn incrementally and usefully, even though it's not simple in total. In fact, I think the two kinds of simplicity are often opposed.

Brainfuck is simple, but not simple to learn to do useful things in with.

I feel Lua has a lot of anti-patterns which makes transitioning to/from other languages difficult. Tables are unintuitive versus other data structures, structure syntax varies from other C-languages, and oddly it uses one-based indexing.

Lua is nice in that it's easy to embed into existing projects, and has an established userbase in game modding communities (Garry's Mod, Minecraft computer mods).

Lua comes in quite high on the "Most Dreaded" list of programming languages and has 1-based indices in a world of 0-basing.

Not exactly something I would recommend ...

"Lua is far simpler" - citation needed 8)

At some stage I will have to get to grips with Lua (Mediawki) but I believe your comment is completely arse about face. No, I wont give any more justification than my assertion.

Unqualified simplicity is useless metric. Brainfuck is about as simple as a language can be, and people can learn it in an afternoon.