Implementing the bare necessary to host and distribute Principia levels from a site (a "level server").
It consists of only one PHP script, apZodIaL1/x.php which is the endpoint the game uses to download levels (descriptive I know). It will fetch levels inside a levels/ folder that should be put right next to the apZodIaL1 folder.
This needs to be put on the root of a site, i.e. https://example.org/apZodIaL1/x.php. HTTPS is also required, but the game currently does not verify certificates so a self-signed one should work.
To play a level from the server, specify the domain in the protocol link as such:
principia://example.org/play/lvl/db/1
grejer.voxelmanip.se is set up as a level server. To play a level off of it, open this link in your browser:
principia://grejer.voxelmanip.se/play/lvl/db/1
Probably doesn't even meet the minimum requirement for copyright, CC-0 if it does.