Yeah, I think something along the lines of "an existant OS" is an acceptable translation. "To aru" has a subtle connotation implying that it is a standalone thing in its own regard. It's a pretty clever name for a hobby project like this, IMO.

Sorry for going off-topic here to the thread, but ...

As someone studying the language, can you explain what the と portion of the name means? I am aware of the ある (有る) portion, "to exist", and that と is being used here to represent a clause, eg "Xと言った" (X said), "Xと思った" (X thought).

But in this case, there's nothing before とある, so why say と at all in this case? Why not just say あるOS?

I think it's stylistic. The anime series (To aru majutsu no index) uses the same style of "to aru <noun>" instead of "<noun> to aru". It reminds me of Latin, where you can adjust the position of phrases in the sentence for emphasis or rhythm.

Personally, I think of the "to" as emphasizing the specificity of the phrase, if that makes sense. It's not just that "an OS", it's this specific OS that's being referenced by "aru".

Ah, most interesting. Didn't think you were allowed to ever move "X to <verb>" to "to <verb> X", but great to know that this happens. Thank you for the explanation!