Lua is indeed difficult to beat in this respect. If you need performance you can even embedd LuaJIT with a footprint still far under one megabyte. And if you don't like the Lua syntax, there are already good alternatives,e.g. the statically/strongly typed https://github.com/rochus-keller/Oberon which directly generates LuaJIT bytecode (based on https://github.com/rochus-keller/LjTools). Here is a fairly complete list of languages compiling to Lua: https://github.com/hengestone/lua-languages. Gravity could be one of these if need be.
LuaJIT development has effectively halted, and only supports Lua 5.1 (5.3 is current, 5.4 imminent).
I get the feeling that Lua is slowly on its way out because the academic nature of it never meant it had to be more than "good enough" outside it's core strengths.
I think they should have kept a super-light "classic" Lua where ~= still means !=, there are only tables, and all the other quirks (but also speed). Then add official, optional support for classes, lists, dicts, sets. This probably can all be built on top of setmetatable, so be pure lua, but at least it comes as one consistent standard library and not in the form of a fractured ecosystem.
All the mentioned compiles-to-lua Projects tried something similar, but never gained significant traction, probably because of the lack of an official blessing.
> LuaJIT development has effectively halted ... never meant it had to be more than "good enough" outside it's core strengths
That's a wrong impression. Even the original author of LuaJIT still commits regularly and there are dozens of companies maintaining and using it in industrial scale applications, and there are a couple of forks which focus on specific use cases and are independently developed. Not to forget the hundreds of games using Lua as a scripting language.
> only supports Lua 5.1 (5.3 is current, 5.4 imminent).
Which is obviously enough for most people using it including me. I don't see any unique selling point which would force me to update to Lua 5.3 or higher.
> and all the other quirks (but also speed).
Well, do your research. LuaJIT is among the fastest JITs available (e.g. a factor ~1.5 faster in geometric mean than JS V8), but with a much smaller footprint.
> 5.1 / 5.3 -- "don't see any unique selling point" -- "there are a couple of forks"
Doesn't that show that the actual users of Lua and the authors have drifted apart, and the former are not willing to commit to a hard fork or taking over development? Or both sides could come together to form a much-beloved committee. The curse of "good enough".
> quirks / fastest
I think you misunderstood: Yes, it is fast even without LuaJIT, and super easy to embed and integrate - which is why this slow fading away into the embedded only realm would be quite a shame.
But it is also "quirky", and adding some (optional, possibly slower) syntax sugar over it could make it more appealing. Sure, Lua-fans will argue that tables are better than anything, but for those who just want to transfer existing language knowledge are hard to convince, and setmetatable makes everything even weirder.
> this slow fading away into the embedded only realm would be quite a shame.
I assume you mean "embedded use in applications" (i.e. not embedded systems). That's exactly what Lua was designed and built for by its original authors. An that's how it is mostly used.
> adding some (optional, possibly slower) syntax sugar over it could make it more appealing
Lua can do surprisingly much for this lean and simple syntax. If instead you prefer a baroque, pretentious syntax like Python or TypeScript, and are obviously satisfied with Python's performance, you already have a well established solution. And as I've demonstrated e.g. with https://github.com/rochus-keller/Oberon you can replace Lua by a more complex language and still profit from the performance and leanness of LuaJIT.
For me the biggest things with newer luas would be things like the bitwise operators, 32bit numbers and utf8 support. I haven't played with 5.4 yet but the garbage collection changes look rather nice too for some of the embedded work i've done with lua
