So I wanna make a small (64k) demo–nothing super impressive, just for the coding experience. I’ve been wondering, what exactly counts towards a byte count? For example, I could embed Lua as a scripting language once I have a simple demo engine running, but since python comes on pretty much every *nix computer, can I use its interpreter at no cost?
Some might argue that it’s not in the spirit of the demo scene, but I do think it counts as milking every last byte. Plus, Lua is 50k and I don’t want to write a smaller, custom interpreter (which will be buggy).
The general spirit of the thing is that, as a piece of art, any random person ought to be able to download and view your demo. So it’s the base default install of the platform that you’re concerned with. This is why most of the best demos target Windows; DirectX is universally available, and the ability to use those libraries dramatically reduces the amount of code in the demo executable.
The same is true of OSX, but other Linux/UNIX variants are really problematic, because there’s often no such thing as a standard install. And good luck as far as drivers for hardware-accelerated 3D go.
That said, it’s really up to the individual group or competition that you plan to submit your demo to. You’d be best off contacting one of the members or organizers to see what their rules are. If you’re just doing this for yourself, to post on the web, then you get to decide what seems fair. The more restrictions you place on yourself, the more impressive the demo ends up being.
If you’re really serious about a 64k demo, though, you’ll use assembly, not an interpreted language. You only benefit from something like Python if you can get short text to expand into a very complicated function in the stdlib. Most of the places where that matters for a demo are related to graphics and sound, and Python’s stdlib doesn’t provide much (nor should it) in either regard.