Precursor ruin

Structures older than any human record, built by hands that were not hands, for purposes nobody agrees on. Some doors still open on a gesture, some rooms are warm, and the scholars who come here tend to stay longer than they planned.

Light
Dim
Going
Slow

Hear it

Hazards

  • Precursor field. Something in the walls is still switched on. Hair stands up, compasses spin, and now and then a room rearranges the party's sense of up and down. D&D 5e (House rule): House rule: on entering a room touched by the field, each creature makes a DC 13 Wisdom saving throw or has the Incapacitated condition until the end of its next turn as gravity seems to turn.
  • Unbreathable air. There is air, but not air a human can live on: too thin, no oxygen, or the wrong gases. A mask and an oxygen supply are enough where the pressure holds; a full suit where it does not. D&D 5e: A creature holds its breath for 1 + its Constitution modifier minutes (at least 30 seconds), then gains 1 Exhaustion level at the end of each of its turns until it can breathe; it then loses all the Exhaustion it gained this way. Starfinder 2e: Thin atmosphere (GM Core): a few hours make a creature that is not acclimated fatigued; in severely thin air it attempts a Fortitude save every hour or becomes drained 1. With no oxygen at all, use holding breath and suffocating (Player Core). Armour environmental protections cover both. Archives of Nethys

What may happen

  1. A door opens at a gesture someone made by chance.
  2. One room is warm, and the dust on its floor is disturbed.
  3. The glyphs on a wall rearrange themselves while nobody is looking straight at them.
  4. A deep hum rises from below, felt in the teeth more than heard.
  5. A scholar from the last expedition is still here, years later, and does not want to leave.
  6. The walls give off a dim, even light, with no source anyone can find.
  7. The steps are each as high as a person’s waist. Whatever climbed them was large, or did not climb at all.
  8. A rival academic team has fenced off the best gallery and pretends not to see the party. Their leader is polite and furious.
  9. On a ledge sits a smooth object the size of a fist, warm to the touch, which nobody remembers seeing there yesterday.
  10. The ceiling of a dome-shaped room is studded with points of light that match no sky of today. The astronomer thinks they match a very old one.
  11. A pool of clear liquid sits in a basin, perfectly still, untouched by dust, and it does not freeze.
  12. The scholars’ camp at the entrance has a kettle always on, a library of printed notes and three people who argue all day.
  13. A narrow tunnel has been cut into a sealed wall with ordinary tools. Looters got here first, and stopped halfway.
  14. A door with no hinges, no frame and no seam stands open, and nobody saw it open.
  15. A voice in this hall comes back a moment too late, and slightly lower than it went out.
  16. A wall is pierced with thousands of small holes in a pattern that repeats, with one hole missing each time.
  17. The corridor slopes down so gently that only a dropped marble shows it. After an hour, the party is far deeper than the map says.
  18. The dating results come back from orbit. The number has so many zeroes that the lab asks for a second sample.
  19. Scratched beside an archway, in plain letters: a name, a date and "turn back at the blue room". The date is twenty years old.
  20. Behind a sealed door the instruments read air, breathable or nearly, kept in for who knows how long.
  21. The dust in this gallery lies perfectly smooth, without one footprint, though the scholars swear they walked here last week.
  22. Rods of clear crystal stand in rows like an orchard. Each rings a different note when touched, and together they make a chord.
  23. A ring of seats shaped for bodies nobody can quite picture faces a blank wall. The xenologist sits in one, and stays a long time.
  24. A room whose floor maps the surrounding country in raised relief, accurate except for a river that no longer exists.
  25. At night the whole ruin glows faintly from within, and the camp sleeps in its light.

Adventure hooks

  1. A door that has been sealed for the whole history of the dig opened by itself this morning.
  2. The lead scholar insists she has translated a warning, and the sponsors want her removed from the site.
  3. A room in the ruin shows the stars as they will be in a thousand years.
  4. Every expedition that took an artefact off-world has lost its ship within the year.

Who and what is met

Each is an SRD stat block under another name, as game masters reskin them.

Other places among the stars

Orbital station, Derelict ship, Colony outpost, Asteroid field, Gas giant orbit, Deep space relay, Terraforming works, Prison hulk, Research lab, Crashed freighter, Nebula, Neon city, Junktown, Spaceport, War front, Alien hive, Living ship, Undersea base, Lava foundry

This work includes material from the System Reference Document 5.2.1 ("SRD 5.2.1") by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.

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