A complete, ready-to-play D&D adventure in one click — made to run the whole night live at the table, on any device.
One-Shot is a Dungeon Master's tool for Dungeons & Dragons 2024 (5.5e). Click once and you get a finished ~4-hour one-shot: a story that actually hangs together, a map, balanced fights, a puzzle, traps, a treasure room and a boss — with all the DM math already done for you. Then you run the whole evening from the same app, live.
No weekend of prep. No "the DM figures it out" gaps. Generate, read, play.
Two languages. English is the default; add
/svto the URL for Swedish, or just switch anytime in the app.
Everything comes from a single seeded generator, so the pieces fit together instead of feeling like a random pile:
- A story with a spine — villain, motive, the hook that pulls the party in, and a twist, all consistent with each other.
- A real map — rooms sized like actual D&D spaces, corridors, secret doors and an optional hidden room, drawn as a clean SVG you can zoom.
- Balanced encounters — monsters and a boss matched to your party's level and size using official 2024 / SRD 5.2 XP math, with action-economy in mind so the boss fight doesn't fall over in one round.
- Puzzles, traps & treasure — with DCs, save types, effects and loot chosen to fit the theme.
- Read-aloud boxed text — atmospheric descriptions you can read straight to the players, written in two voices (fuller for new DMs, terse for veterans) with an optional grimmer tone.
- Secrets, clues & NPCs — reusable clue cards and "how to play them" NPC cards, so improvising never leaves you stuck.
One-Shot isn't just a generator — it's the console you actually run the session from:
- DM mode + a player second screen — put the player view on a TV, tablet or their phones, with fog of war. Your secrets, notes and boss stats cannot leak to it (the player screen only ever receives a whitelisted snapshot).
- Pacing & clock — a session timer shows whether you're on track, how long until the boss, and which rooms you can safely cut if you're running long.
- A combat tracker that knows the rules — initiative, HP, conditions, death saves and concentration, with quiet reminders so you don't have to hold it all in your head.
- Notes & session log — pin notes to any room; the log records the night for you automatically.
- Ambience — optional background audio (built-in generative tracks, or your own YouTube / files / links) that matches each room's mood.
- Session 0 safety tools — tick the topics to avoid and the generator steers around them.
Never run a game before? Turn on beginner mode for extra guidance, take the short "your first night" tour, and lean on the built-in explanations — every rule term has a tap-for-help note. The whole app is built around one idea: make a quick ruling and keep the story moving. You do not need to know every rule to run a great night.
Run games in your sleep? Flip to expert mode for a lean, quiet interface, then get your hands dirty. The structural editor lets you swap monsters, change counts, gold, traps and the boss — with a live XP/difficulty meter watching your back so you always know what you're doing to the balance. Export the finished adventure however your table runs: Markdown, a virtual-tabletop map (.dd2vtt for Foundry / Roll20 / Fantasy Grounds / Owlbear), print / PDF, or QR codes to hand your players. And because nothing is homebrewed, you can trust the numbers.
Same app, three ways to play — pick whatever fits your table.
Open one-shot-smoky-five.vercel.app in any modern browser on phone, tablet or desktop. That's the full app — nothing is cut down.
It's an installable PWA: hit "Install" (desktop) or "Add to Home Screen" (mobile) and it lands on your device like a real app — its own icon, full-screen, and fully offline after the first visit, so it keeps working at a table with no signal. No account, no login; everything is saved locally on your device.
Prefer a real desktop app with no browser in the way? Grab the standalone Windows build from the Releases page. It's a single .exe, no install and fully offline — it bundles the whole app and its own storage, so it runs completely on its own.
Press F11 (or the ⛶ button in the toolbar) to toggle fullscreen. Because the build isn't code-signed, Windows SmartScreen may say "Windows protected your PC" the first time → More info → Run anyway. You can also build it yourself from source with npx tauri build (it uses Tauri).
Today: install the web app — open the site in Chrome and choose Add to Home Screen. You get an offline, full-screen, app-like install with its own icon, no app store needed. A native Google Play build is on the roadmap.
The casual surface hides a genuinely deep engine:
- Deterministic by design — the same seed and settings always produce the exact same adventure, down to the last trap. Share a seed and a friend gets your dungeon back, byte-for-byte.
- Rules-accurate, no homebrew — 238 monsters and 97 magic items, every stat cross-checked against the SRD 5.2; XP, encounter, treasure and DC math all follow official D&D 2024 / 5.5e.
- Time that's actually realistic — instead of hand-waving the retired "adventuring day", it budgets encounters and scenes against a credible ~3.5h of real play, capped so a "4-hour" one-shot really is one.
- Leak-proof player view — the second screen is fed a strict whitelist, so DM secrets, notes and edits can never reach it, by construction.
- Fully client-side — the generator and all your data live in the browser; there's no backend, no account and nothing to sign up for.
Requires Node.js 18+.
npm install # once
npm run dev # start the dev serverOther useful commands:
npm run typecheck # TypeScript check
npm run build # production build → dist/
npm run preview # preview the production build
npx tauri build # build the Windows desktop appReact · TypeScript · Vite · Tailwind · Zustand · SVG map · PWA · Tauri (desktop).
Fully client-side: the procedural generator and all saved data live in the browser, so the app works with no connection at the table.
One-Shot is built by a solo developer, with Claude (Anthropic's AI) as a coding partner throughout.
This is v1.0.0 — the first public release. A lot has been tested along the way: the 2024 rules math, the generator's determinism, and the tools you actually run a session with. Even so, a project this size will still have bugs and mistakes that neither of us caught, and not every feature has been through a real table yet. If something looks wrong, breaks, or just doesn't add up at the table, open an issue or drop by Discord — a concrete report, ideally with the seed, is the most useful thing you can send my way.
© 2026 Wiseman. Licensed under the GNU Affero General Public License v3.0 (AGPL-3.0) — see LICENSE. You're free to use, study, modify and share the code under the AGPL terms; notably, if you run a modified version as a network service, you must make your source available to its users under the same license.
The app copies no book text. It uses original flavor text plus material from the D&D System Reference Document 5.2 (© Wizards of the Coast, CC BY 4.0), icons from game-icons.net (CC BY 3.0) and the Cinzel & IM Fell English typefaces (SIL Open Font License 1.1) — all credited within the app. Unofficial project, not affiliated with Wizards of the Coast.