The Barrow of Vethkar

A single-file, browser-based D&D-style dungeon crawl — play solo, or host up to three friends over a peer-to-peer connection. No build step, no server-side game state: index.html is the entire game.

Play it live: https://barrow-of-vethkar.vercel.app/

What it is

A deterministic rules engine (dice, hit points, inventory, death — all decided in code, never by an AI) paired with a narrator that turns each outcome into prose. Play by picking from 3–4 concrete choices each turn, or type what you want to do in plain English — a small parser maps free text to the same underlying actions.

• Solo or multiplayer. Host a game and read out the four-letter room code; up to three friends join as their own characters. The host's browser runs the rules; guests send intents and receive results, so a modified guest client can't cheat.

• Five dungeons to choose from at character creation — a barrow, a drowned chancel, a wood that will not stop growing, the Sunken Reef (fully underwater, with teleport traps), and the Underline, the abandoned stations and sewers below New York City (track rats, sewer gators, graffiti wraiths, a ghost Motorman, and Gutterscale, the White Queen Below, guarding the Founder's Token at City Hall Loop) — each with its own monsters, rooms, atmosphere and prize.

• Eight classes, ten ancestries (including Triton), six backgrounds, each with mechanical effects (not just flavor text) built on the SRD 5.2.1 ruleset.

• Levelling up. XP earns levels; every level grants 2 ability points the player spends on the abilities they choose (max 20). Points can be spent any time — mid-fight, between turns, or on the victory screen — and never cost an action.

• Favorite characters. Save any character (name, look, level, XP and ability scores) to the browser and bring them into a new run; each run starts with the class's own kit. Every player, guests included, can save; saved favorites update automatically as the character progresses.

• Status effects (poisoned, stunned, burning and more) that last one or several turns, shown as chips on the turn bar.

• Keys and locks. Find a rusty key and a locked chest or door turns up ahead with treasure behind it — unless it's a mimic.

• Cutting Words insults are shown to every player at the table.

• Woodcut silhouette art, all vector and drawn in code (no image downloads): an animated battle scene behind the story whenever a monster attacks, a scene for each area as the party enters it (entrance, interiors and vault, tinted per dungeon), and an icon for every item — shown as a card when it's found and beside it in the inventory.

• The Roots, a skill tree you grow yourself. Every level after the first earns a root. Open the Roots tab at any time (it never costs a turn) and grow from any root you already have, in any direction, down into the barrow. Deeper ground holds stronger roots; capstones only grow in The Deep. Every class has three branches, every ancestry adds one root, and every root is enforced by the rules engine. Saved favorites and old saves carry over: their level becomes roots to grow. Spec: specs/001-roots-skill-tree/.

• Traitor Mode (2+ players): the host can secretly arm it. Arming it is silent — nobody else is told the mode is even on, and the state their browser receives says it was never switched on. One party member is chosen at random as the traitor, invisibly to everyone, even the host's own screen. They get secret sabotage/aid actions the rest of the party only ever sees as ordinary bad luck or good fortune. Once the real dungeon boss falls, the traitor alone is told the way is open, and chooses their own moment to turn — one turn later, on the last step out, or never. When they do, they become the true final boss under a name only they chose.

• Table music. Paste a YouTube link and every viewer gets their own embedded player with real controls; the host's pick just seeds what's playing for everyone.

• Optional AI narration, off by default and never load-bearing:

  • Connect local AI — talks to a model running on your own machine via Ollama.
  • Connect cloud AI — no install required; calls this deployment's own /api/narrate function, which rewords outcomes via Groq's free-tier API. See Cloud AI setup below to turn it on.

  Either way, the model only ever rewrites the sentence describing an outcome that dice and rules have already locked in — it never decides a hit, a roll, or a death.

• Optional AI Dungeon Master (cloud AI): /api/dm lets the model act in the rooms the party enters (a wandering monster, a trap, hidden loot, a helping hand) and judge freeform actions. It only ever chooses from fixed menus the game offers, and the dice still decide every outcome.

• Manual dice-rolling ceremony, sound effects, mobile-friendly layout, and save/load to a local file — all client-side, no account or database.

Running it

Just open index.html in a browser for solo play. Multiplayer hosting and the YouTube embed need a real https:// origin (browsers block both from a local file:// page), which is what the Vercel deployment above provides — open an issue or fork if you want to self-host elsewhere.

Cloud AI setup

The "Connect cloud AI" button (and the AI Dungeon Master, /api/dm) needs one environment variable on whatever deployment is serving the game:

Variable	Required	Purpose
GROQ_API_KEY	yes	A free key from console.groq.com/keys. Without it, /api/narrate returns a clean "not configured" response and the game falls back to built-in narration.
NARRATE_CLIENT_KEY	no	If set, /api/narrate and /api/dm only accepts requests carrying a matching x-barrow-key header (the client already sends the fixed value barrow-of-vethkar). This is a light deterrent against random bots hitting the endpoint, not real security — the value is visible in this repo's own client code.

On Vercel: Project → Settings → Environment Variables → add GROQ_API_KEY → redeploy.

Licensing

Uses content from the SRD 5.2.1, © Wizards of the Coast, licensed under CC-BY-4.0. "Dungeons & Dragons" and the D&D logo are trademarks of Wizards of the Coast and are not used here.