I have never heard of it but watching videos it seems to be a puzzle game with an interesting game mechanics: you can "change the code game is executing" right inside the game.

It's not a facade or a gimmick, either; they ship a lua decompiler and the hacking UI is based on decompilation/recompilation of the game scripts.

Is the portion of the code the user can hack being run in a separate sandboxed execution context, or can the user really change everything written in Lua should he try hard enough...?

Brandon (I think that's his name) actually went out of his way to avoid sandboxing and deliver the premise as authentically as possible. He's talked about it in a few videos in more detail - https://www.youtube.com/watch?v=1FgC_284eNU#t=88

I didn't know that! It looked like a carefully prescripted game feature, but decompiler and real assembly make it even more interesting. :) (I already bought the game)

grim fandango was written in lua? :O

...and Far Cry, and Baldur's Gate, and WoW, and Angry Birds, and...

Lua is ubiquitous in game programming (as a scripting language), see e.g.: http://en.wikipedia.org/wiki/Category:Lua-scripted_video_gam... or browse through some game programming related job openings.

I wish is a little bit more ubiquitous everywhere else. It's a great language and would have been a far better Javascript!

I always liken Lua to "JavaScript, with all the bad parts removed".

I should have added "already", I know lua is very common now, I didn't know it was common in 1997.

It was AFAIK the first game to use Lua, and it influenced the rest of the industry.

Ah yes:

"Soon after the article in Dr. Dobb's, we received several messages about Lua. One of the first messages was the following:"

    From: Bret Mogilefsky <mogul@lucasarts.com>
    To: "'lua@icad.puc-rio.br'" <lua@icad.puc-rio.br>
    Subject: LUA rocks!  Question, too.
    Date: Thu, 9 Jan 1997 13:21:41 -0800
 
    Hi there...
 
    After reading the Dr. Dobbs article on Lua I was very eager to check it
    out, and so far it has exceeded my expectations in every way!  It's
    elegance and simplicity astound me.  Congratulations on developing such
    a well-thought out language.
 
    Some background: I am working on an adventure game for the LucasArts
    Entertainment Co., and I want to try replacing our older adventure game
    scripting language, SCUMM, with Lua.

    [...]

http://www.lua.org/history.html

Note that before that, Lucasarts had a custom execution environment for their games, for portability reasons (SCUMM). Grim Fandango uses GrimE, sort of a successor to that.

I would assume that LUA was a way to move towards something common as a scripting language in GrimE.

http://en.wikipedia.org/wiki/SCUMM http://en.wikipedia.org/wiki/LucasArts_adventure_games#3D_gr...

They weren't quite "written" in lua, but more had their higher level logic (events, stats, game logic) scripted in lua.

It's kind of a small point, I just don't want somebody to get the idea to write an actual game engine in lua.

the game engine was likely c++, and the scripts (Fx, behaviors, etc) were in Lua. It's a common setup.

my surprise was that this was true 17 years ago :)

Lua is 20 years old :)

My brother had a demo of Grim Fandango in a ZIP archive, and it didn't include the Lua DLL. When we reran it years later, we first had to recompile Lua (3.1?) before the game would run.

That's how I learned it was using Lua. I believe it was the first large scale use of Lua in a game, certainly the first I encountered.