I will use this topic to collect curious tidbits I have found on the web related to Opus. (Better than creating a new post for each, yes?)
Why? Because it isn't enough to enjoy this Magnum Opus, it is also nice to see that it is seen as such. Or maybe I just have too much free time and stalk "Directory Opus" in a dozen places with my feed reader and can't keep up what I found for myself.
Starting with a comment on Reddit praising @Jon:
On an amusing and delicious side note, the developer is an Elder Nerd from the Amiga days and he is also the Final Boss when it comes to battling pirates on the high seas. If you can get a cracked version of Directory Opus running you are LEGIT. Like, for real. I only bring this up because it really is rather amazing just how devious and relentless this guy has been - and trust me YOU aren't going to crack it.