I was initially confused - I thought this was going to be an OS implemented in Lua, but it's a Linux distribution which has special sandboxing for Lua: http://luaos.net/docs/manual.php#4.
I've poked around a decent amount of the site, and I'm still not clear on what this is a solution to.
Special Sandboxing that, I think, is implemented in Java. So this is an OS in the sense that it only depends on having a JVM and Lua interpreter installed.
Not that this is a great metric (especially when the source languages are taken into account), but here are the LOC counts in the project:
I've poked around a decent amount of the site, and I'm still not clear on what this is a solution to.