Where Lua Is Actually Used 

Out of the few programming languages I've messed with, I'm most familiar with lua just from messing with Roblox studio.

My favorite game Project Zomboid uses Lua as a modding language

Lua is also used in opencomputers and computercraft (mods for minecraft) its pretty cool

„I dont have time to make Snake in Lua or Python“ proceeds to read some reddit thread. Result very good time managment

Lua and Elixir are Brazilian pride

basically.... Lua is actually commonly used on Roblox.

LaTeX uses Lua

lua is an incredibly simple language and a lot of people like it because of its metatables

Don't think mpv came up. It's a video player written in C with lua (and javascript) bindings. The core UI elements are all drawn with built in lua scripts. There's plenty of custom control interfaces people have hacked together for specific needs, e.g. EQ, tone curves, projection, etc. There's even a REPL, I have my own fork with extended autocompletions and fennel support B)

Lua (mostly LuaJIT because of it's ffi module) is very broadly used in hacks/cheats for games. Particularly in CS:GO it can do some pretty fun stuff - the community managed to implement countless features not targeting towards gaining an advantage - you can apply custom postprocessing effects, use custom models & textures for EVERYTHING, modify the user interface as you want, spawn random effects/objects and so on. It's really fun when you dig into the rabbit hole, but sadly Valve deprecated CS:GO

All of the game scripts for Warframe are written in Lua.

Lua is used on Texas Instruments' graphical calculator called Nspire. You can write interactive applications or functions for students (or for yourself) on the PC-side program, which then can be distributed and run on handhelds.

More on Love2D, it is the engine used in Balatro which is a pretty popular indie game made by a solo dev, was the first time I heard of Love2D

Introduced Lua to a scripting system to handle interlocking and signal logic for train infrastructure simulation, literally the simplest thing to just throw in with a short timeframe and be working

Garrysmod and Lua got me into programming. I've used Lua for around 15 years now, and I still love it just as much as I did from the beginning.

Don't Starve Together uses it too, not only is it's modding API in Lua, most of the base game minus the performance-critical engine stuff is too, which makes it really easy to mod. When you want to do something similar to something already in the game, or you are confused about how certain parts of the API work, you can just look at the game's code and check! This also lets them get away with having zero documentation for their modding APIs, and allows you to mess with stuff without needing the devs to build an API for it.

Started to use lua to mod trailmakers, it's probably my favourite language, i only wish it had the recognition of python (aka all those libraries) given how good it is (i am not a big python fan)

A super popular game right now Helldivers 2 uses Stingray/Bitsquid; a Lua based game engine. The game engine itself has been discontinued, but the developers has access to the code so it's pretty much a proprietary engine at this point. Vermintide, another game built in the same engine, has apparently more than 1 million lines of Lua code.

LUA is also often used as the scripting language in cheats

I actually really like the syntax lua uses, it reads really literally ("IF this THEN do that END" for example) and some of my favorite games use it so thats a plus too