I'm not familiar with CoreGames but I can easily guess the presence of
_ENV, here, and of a concurrency model. These are programming models where you have similar entities running concurrently, each in its dedicated context, and possibly with mechanism to synchronize and communicate with each other.
Is this only possible with Lua? No, of course: all common programming languages are Turing complete so they are equivalent in what you can do with them. The differences are in convenience, expressivity, performance, etc., but what you can do with one you can theoretically do with any other.
Is this normal? Well, yes. If you think about it, it's essentially what all multi-tasking operating systems do: they run several processes concurrently, each defined by an executable (the 'script'), and each in its own context. Similar concurrency models are also commonly implemented within applications, using facilities provided by most programming languages either via core constructs or via specific libraries. Threads, coroutines, etc, all fall in this category.
(As a matter of fact, I've developed a couple of libraries that could be used to implement such kinds of systems:
MoonAgents, and
MoonSC ).
