So, yeah, some time has went by. The project has been sitting idle for a few months, but recently I've picked it up again and began tinkering. After remodelling some internals workings a bit and implementing a few important elements, like arrays and dictionaries, I think I can update the thread.

(Yes, I know the loop should go to :sqrt $LIMIT.)

Above is example code for the Sieve of Eratosthenes, demonstrating the use of arrays and user-defined functions. I've also updated the manual to include the relevant info. Of course, the documentation is still far from complete, but I think it's enough to get one started, and given the fact that the interpreter is still yet to be released as a downloadable version... Well, let's say I'm currently more focused on extending and improving the code, rather than writing the manuals.

So, if anyone's interested, the links from the first post are still valid.
Manual, to learn the syntax: http://pi.svgames.pl/?awful
Playground, to wreak havoc with your scripts: http://pi.svgames.pl/form.cgi