The Tenebris Somnia demo is a separate free application that runs about 20 minutes and covers only the opening apartments on Floor 3. It has two puzzle chains — the red wax seal on the Study door and the floor-symbol puzzle — and it ends inside that study sequence.

What the demo covers

  • The demo is listed as its own application with the full game registered as its parent, and it is still downloadable free on its own.
  • It first appeared on September 6, 2023, was updated again in October 2024, and was updated as Demo v0.4 for Steam Next Fest in February 2025.
  • The run follows the opening of the story: after the prologue you use the Apartment Key to enter Iván's block on Floor 3 and start working through the rooms.
  • It ends inside the study sequence, and its content and its endings are different from the full release. A demo walkthrough is not a shortened version of the full walkthrough, so treat anything below Floor 3 in the full-game guides as out of scope, and check the demo's own version before following a full-release route. The full-release route is in the walkthrough.

The sealed Study door

The Study door is covered in a red wax seal, and the fix is a compound you make yourself.

  1. Take the glass and the developing chemical.
  2. Take blood from the cracked bathroom mirror, and combine it with the glass to get Glass with Blood.
  3. Combine that with the developing chemical.
  4. Put the mixture at the exposed window, where it heats into Auritsatio.
  5. Use the Auritsatio on the red wax to open the door.

Two items are needed on the way there. The Old Book on the living-room floor carries the clues for the sealing wax, and the Wrench in the bathtub is what gets the bedroom window boarded up so sunlight can reach the mixture. You equip the wrench from the inventory and use it to defend yourself against the creature that comes for you.

The floor-symbol puzzle

The television flashes a sequence of symbols far too quickly to read from a single pass, and the pressure plates on the floor deactivate quickly, so you have to study the route before you step off it.

  1. Find the TV remote.
  2. Put batteries into it. A television showing nothing but static is the sign that the remote is dead.
  3. Switch the remote on.
  4. Watch the television and write the symbol sequence down.
  5. Step on the matching floor plates outside the bedroom door, in the same order.

Demo v0.4 changes in the Tenebris Somnia demo walkthrough

  • You can now only interact with an object if you are facing it.
  • The second-floor television plays constant noise, so you know something has to be done there.
  • The camera was adjusted to show more of the game.

If you are following an older demo video, the interaction and camera behaviour in it may not match the current build.

The two demo puzzles

The same two puzzles carry into the full release with more steps attached, and the full game adds several more that have no demo counterpart. The full list of those is in the puzzle hub.