Red Dead Redemption 2 is a game with layers. On the surface, it's a hyper-realistic survival narrative – an anti-hero tale that deconstructs America's rugged individualist ideal. Rockstar Games created a world that emphasises 'This is real, and if you treat this like any other video game, you're going to die. A lot'. You have to oil and clean your guns when they rust. You have to change your clothing when you head into the mountains. Knocking over a person over in town will get you reported to the sheriff, who, if you're nice, might let you off with a warning.

But the more you play this game, the more you realise there's something fantastical and creepy right beneath the surface of its presentation. It's more akin to Southern Gothic than spaghetti Western, with an artifice of normalcy that conceals unnatural occurrences.

You'll start seeing weird things when you diverge from the story missions, the stranger missions, and every other directive the game gives you, and begin to act on your own. Some of your first self-directed explorations will be of the random homes and shacks that dot the landscape, you'll see them in your peripheral vision on the way to a robbery or when heading back to camp, and you'll begin to wonder who resides there, and what lives have they made for themselves in this unforgiving place?

The answers are usually mundane: you'll be able to walk around the property, but the doors and windows will be locked or you'll see the inhabitants milling about outside, living their lives. Every so often, though, you'll get a shock. The music will change to minor chords, and you'll come across some grotesque tableau. These scenes tell stories, and if you take it one step further, and follow the clues, you might unearth something truly bizarre.

Head to this location on the map to find a creepy shack © Rockstar Games

Take, for example, an abandoned shack in New Hanover (circled above in red). When you step inside, you'll find a number of skeletons. Most of them are lying in beds, the sheeting little more than rotting tatters. Clearly, something terrible happened here.

At the front of the shack is a seated skeleton © Rockstar Games

At the front of the room is the skeleton of a cult leader propped up in a chair. And next to him is a letter you can read. It says the following:

At the second hour under the half moon

By the great love and grace of our saviour Kuhkowaba

Voyager of time and galaxies

We cast off our corporal shells

So his vessel can take our spirits to the promised realm

To live in peace and power until the two thousandth year

When we will return for the new chosen

And worship once again at the peak of Mount Shann

In his love we rejoice always.

If you show up to the cabin later that night at 2:00am (use a timepiece to ensure your punctuality), you'll notice a green light shining from the sky down through the holes in the roof. Look up via first person perspective mode, and you'll see a shimmering UFO hovering above you. It'll disappear if you head outside the cabin, so just watch it through the roof and take a few pictures if you'd like.

The penultimate line in the poem leads to another UFO: 'And worship once again at the peak of Mount Shann'. Head to the location circled below in red, and if you find a UFO cult camp further down the slope, don't stop there – you have to situate yourself at very the peak of Mount Shann. Also note that the terrain up there is particularly treacherous. If you love your horse, and have spent the last few hours getting him to trust you, leave him further down the mountain and hike it on foot.

Head to the peak of Mount Shann © Rockstar Games

Starting at around 1:00am a UFO will appear in the sky. It glows and hovers for awhile, and then it flies away. It lasts even less time than the first UFO.

This is not the first time that Rockstar Games has used UFOs in their titles. There was an entire alien conspiracy investigation in Grand Theft Auto V, about a series of glyphs near the peak of Mount Chiliad. The mystery united an entire community of conspiracy enthusiasts and data miners, who pored through the game's code to uncover as much as they could.

We interviewed Reddit user bluntsarebest, who moderated subreddit /r/ChiliadMystery in its heyday, about the latest mysteries in Red Dead Redemption 2. He expressed positive enthusiasm, and he namechecked a brand new subreddit, /r/reddeadmysteries , which is dedicated to discussing them.

"Unfortunately, most of the 'mysteries' were all laid out in the official strategy guide so they didn't require huge online efforts to solve," said bluntsarebest. "Although, there does seem to be a few odds and ends scattered around the map for which we don't have definitive explanations. I haven't heard of any Bigfoot sightings yet, but who knows what else is hidden in that frontier?"

He also alluded to some other mysteries the online community is currently exploring – vampires, a time traveller, giants, and religious cults. It's an entire underbelly of sci-fi and horror spookiness.

In Grand Theft Auto V, a certain level of 'out there' shenanigans was expected. The entire game was a satire, which allowed it to generate scenarios and characters that were more representative of ideas than of actual places and people, but in a game as detailed and reality-based as Red Dead Redemption 2, the existence of aliens or vampires seems incongruous. And it's unsettling to see evidence of such fantastical creatures in a world where everything is so carefully constructed.