The Aeternus Trailhead: Return to Center

Yesterday, ARGNet received a letter in the mail from an anonymous party. Inside the outer envelope was a letter wrapped around an unsealed envelope, containing what I would soon learn is the trailhead to an alternate reality game centered around the company Aeternus Center. And within an hour of opening the letter, I mailed the contents off to make this someone else’s problem. But to explain why, it’s necessary to learn a little more about this enigmatic trailhead.

The letter contained within the outer envelope was straight to the point:

Subject: Aeternus Center

Hi ARGNet,

Received the following in the mail a couple days ago regarding some sort of ‘company’, though the contents seem ARG-ish and the name it was addressed to was only used in ARG contexts. Unfortunately I don’t have time to investigate with classes going on, but also want it somewhere accessible in case the contents are important for whatever thing is going on.

Out of concern for their privacy, the anonymous sender took a permanent marker to blank out their return address and postmark before forwarding the letter they received from the Aeternus Center. Even if someone claimed they were the original sender, I’d have no way of verifying that fact. The only unredacted information on the envelope was the Center’s return address: a PO Box in Cambridge, Massachussetts.

The contents of the Aeternus Center’s letter was thankfully more forthcoming, and included:

The Aeternus Center website provides an impressively vague description of a company focused on “discovery and experimentation”, after its founder Alexander discovered “a strange compound with wonderous properties” back in 1990. The company then structured itself around four main divisions: Precursor, Archivist, Explorer, and Oracle.

Logging into the Aeternus Center’s intranet site with the credentials provided in the Welcome letter amusingly throws “security breach” warnings, along with annotated comments on the website’s main content alongside a message flagging that “spatiotemporal linkage has been established”, and warning of corresponding spatiotemporal anomalies.

The corporate intranet’s database may be available, but its “Tower” and “AE Console” options remain grayed out: meanwhile, the scrawled text on the welcome letter and coded message remain unsolved. That, and figuring out what purpose a coin and key might serve.

Which brings us back to why I’d get rid of a trailhead letter, immediately after receiving it. After noticing that Aeturnus Center’s return address is a PO Box in Cambridge and that the trailhead contained a key that might be described as PO Box-sized, the fine folks at Geekbeat Radio kindly agreed to check out the post office, figure out if the box number exists, and then see if the key fits. After all, there’s only a few shreds of that internal memo, and the Bicycle playing card also only contains part of a message.

This ARG trailhead has seen quite a bit of travel: first, the Aeternus Center mailed an invitation to join the company to an anonymous party. Then, that individual mailed the letter to ARGNet. And now, the trailhead is on its way to its new home in the Boston area. Will the trip prove to be fruitful? Who knows – but I’m already entertained by the game.

While it’s entirely possible the anonymous sender exists, I suspect they were a clever conceit to abide by even the most strict interpretation of “this is not a game”. By sending a letter to ARGNet from an overwhelmed fan of ARGs who doesn’t have time to investigate themselves, the claim that it’s a game and the trailhead’s in-universe verisimilitude are kept separate, allowing the game to enjoy the best of both worlds. And while these same messages ring hollow when sent as emailed tips from “players” who “stumbled across the game”, setting up a story-within-a-story with a matryoshka doll’s worth of envelopes just feels right.

To dive in deeper to the world of Aeturnus Center, check out the game’s website at Aeternus.Center. There’s phone numbers to call, emails to contact, puzzles to solve, and possibly even intranets to hack while we wait to see if the key fits.

UPDATE: additional letters have been spotted in the wild.
Using a ” ⬛💡” on the page with I I I T written in black marker reveals the word “INITIATE”, which provides helpful information for the Aeternus intranet. The key, however, does not fit in the PO Box. Thanks to Geekbeat Radio, for confirming the wild supposition was just that!

To join the community investigating Aeternus, check out their Discord server.


  1. When you go to and check out the site’s SSL certificate, it shows that it’s a certificate issued to “”. When visiting, it appears to be a Thai football betting website. The first and only snapshot of that website on the wayback machine originates from august 8 2020. The website links to a Line (chat app) profile. I haven’t checked the Line profile, but it might be a lead.

    Ufa81 does not really seem related to Aeternus, but I do wonder why the Aeternus SSL certificate had Ufa81 in it as its subject.

  2. I found something that might help. I was purusing the HTML file of the website and found this nugget.

    It does say TODO, so I am inclined to believe this may be nothing. However, if you hit a wall, it is a path to pursue.

    • You can manipulate the data on the page to get access to the “internal” page. Not much there but figured I’d post what it said

      Internal Systems are currently down due to a data breach.
      If you need any help, please contact internal@.

    • Zxnaderisacoolname

      November 20, 2020 at 6:40 pm

      Im confused im checking the casino and there is no link

  3. TODO(magus): Hello there. We have much to talk about, let me know you found this at magus@

  4. Discovered a pretty specific username mentioned: FinisAevum, who mentioned a twitter. Failed to find that, so instead I just searched it at large and found this:

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