I imagine a lot of Dungeons & Dragons players have done a real-life escape or puzzle room. Here's one to challenge their characters!
This is a stand-alone adventure intended for you to work into your campaign if you are experiencing writer's block or if your players go somewhere unexpected. Feel free change names and other details around to best suit your world. This adventure works best as either a stand-alone location when the party needs to find some long-lost artifact, or as a section of a larger dungeon.
This adventure is designed for three or more level 3 characters. Creatures from the Monster Manual (abbreviated MM) are used. Many of these creatures are listed in a range of numbers. Use the largest number for groups of five or more players, the smallest number for groups of three players, and the average for groups of four.
1. Central Hub
The party enters through the southern doors, which lock from the outside after closing. The angular stone walls and smooth floors are covered with undisturbed dust. The rooms here are all dark, except for dim light coming from areas 3 and 7, and very bright light from area 5.
A door to the north has six keyholes and warded with spells to prevent lock-picking, as well as knock and similar spells. Each of the six keys can be found in the adjoining passages.
Every passage has an inscription above it, written in a runic cypher (see the following area descriptions). Since this is a code, and not a language, the spell comprehend languages does not allow characters to understand it. Runes have been substitute for capital letters for ease of communication and decipherment.
Three chunks of a stone tablet sit on a pedestal in the center area. These provide a clue to deciphering the code. Additional pieces can be found in some of the areas. Each time pieces of the tablet are discovered, roll a d6 to determine which sections the players obtain.
2. Crypt
Inscription: SZAB TAJU TGUA
There is a bronze fire pit in the center of the room, containing only ash. Seven stone sarcophagi are mounted against the wall, containing a mummy (MM pg. 228) and 2-4 skeletons (MM pg. 272).
The undead aggressively attack anyone who intrudes in their crypt, even pursuing them outside. However, if a fire is lit in the center pit, they will become frightened and retreat into their sarcophagi, leaving the party alone. Some sort of fuel (such as pieces of furniture from area 7) must be placed in the pit in order for a fire to catch long enough for this to happen.
The mummy carries a bronze key to the door in area 1 on a simple string around its neck. One of the sarcophagi that does not contain an undead creature contains instead a fragment of the stone tablet.
3. Game Room
Inscription: FJSA GV OVA
This room is set up as a chessboard with human-sized pieces standing as marked on the map. The white pieces glow with a faint light. If you have a chess set, it would be useful to set up for the players to see. The white pieces obey a verbal command from the players, or move easily at a touch, despite their large size and weight. The black pieces do not respond or move easily. If repeated attempts to move them are made, they animate and attack (see below).
It is possible to checkmate Black in one move, by capturing the pawn diagonal from the black king with White's bishop. If this move is made, a compartment opens in the Black king, displaying an obsidian key that fits the door in area 1.
If Black is not checkmated in one move, the king and 1-3 other pieces animate and attack the party (as animated armors, MM pg. 19). Upon defeat, the king's compartment opens as previously mentioned.
One of the White knights carries a mirror shield (see below), which is apparent if the piece is inspected. It can be easily pried off of the chess piece.
Mirror Shield
Armor (shield), uncommon (requires attunement)
This round steel shield has a flat face that is polished to reflect as clearly as the finest mirror.
While holding this shield, ranged spell attacks have disadvantage against you.
4. Tunnel of Smoke
Inscription: TGVP SZA TJV
This area is filled with dark billowing smoke that restricts visibility to only five feet in any direction. Lurking inside are 6-10 smoke mephits (MM pg. 217) who invisible as long as they remain covered by the smoke.
Gust of wind or a similar effect can temporarily remove the magical smoke, as well as the mephits, but it returns five minutes later along with the creatures.
At the end of the tunnel is a pedestal with an iron key to the door in area 1. If anyone searches the tunnel, they may find a fragment of the stone tablet, but they must succeed on a DC 20 Wisdom (Perception) check if the tunnel is filled with smoke.
5. Tunnel of Light
Inscription: SZA HVGEZSN NZGAWP
Thin beams of bright energy criss-cross this tunnel haphazardly. A pedestal with a gold key on top of it is clearly visible about 60 feet away. If a character wishes to cautiously avoid the beams, they may move up to half their base movement per turn and must succeed on a DC 15 Dexterity (Acrobatics) check or take 2d8 radiant damage. A character who has attuned to the mirror shield (see area 3) and uses it to block the beams can move at this pace without making checks. If a character dashes or otherwise moves heedlessly down the tunnel, they take 1d8 radiant damage for every 5 ft of movement.
The gold key sitting on the pedestal fits one of the locks in the door of area 1. Squeezed between the back of the pedestal and the wall is a wind fan (Dungeon Master's Guide pg. 213).
6. Maze
Inscription: TOWWOI SZA WATS
If you normally draw maps for your player, this is a good opportunity to simply describe what they see and force them to try and map the maze.
Any time any of the characters turns toward a dead end, roll a d20. The first time you roll a 1-10, the party hears the footsteps and snorting of a large creature that seems to echo throughout the entire area. The second time you roll a 1-10, the party encounters a minotaur skeleton (MM pg. 273) and 1-3 shadows (MM pg. 269).
A silver key to the door in area 1 sits on the pedestal marked on the map as A. One of the stone tablet fragments lies on the floor at B.
7. Study
Inscription: FJHA GS VOOV
The floor of this chamber is covered in bits of broken wooden furniture, with a large stone sundial in the middle. The walls are all set with wooden bookcases filled with tomes. Floating in the air spread around the room is a will-o'-wisp (MM pg. 301) and 2-6 smaller wisps of light (count as steam mephits, but doing lightning damage instead of fire). The mess of furniture causes the ground to count as difficult terrain.
Light from these creatures diffuses any shadow that would fall on the sundial. If light is ever only coming from the side opposite the doorway, the sundial's shadow falls on the noon position and a secret chamber unlocks in its side, which contains a copper key for the door in area 1.
The books crumble at a touch and are mostly useless. However, if a character searches the bookshelves and succeeds on a DC 15 Intelligence (Investigation) check, they find a map of area 6. The location of the key in that area is not marked however.