rollmons

A single-player Pokémon draft autobattler that runs entirely in the browser. Roll six Pokémon through a generation × type slot machine, pick each one's set, then watch an AI pilot your team through a ten-battle boss gauntlet and post the run to a leaderboard.

Play it: https://rollmon.gg — no install, no account needed to play (one is needed only to post a score). Works on phones; English, 中文 and 日本語.

How it is built: the battle AI is poke-engine (Rust) compiled to WebAssembly, and @pkmn/sim (Pokémon Showdown's simulator) referees, both in a Web Worker on the player's machine. There is no battle server: the site is static, and the only backend is one small function for accounts, the leaderboard and feedback. v1, which ran foul-play against a local Showdown server and shipped as a macOS app, is archived at ziangit/rollmons; none of its AI client remains here.

Screenshots

Title & slot roller	Draft — five candidates per cell, rarity by tier
Loadout — one set per Pokémon, Mega opt-in	Pool — 18×9 type-by-debut-generation matrix
Battle theater — live replay, bosses revealed one at a time	Results — record, damage breakdown, score, MVP

How a run works

1. Draft — six rounds. Each round locks a cell (type × generation of debut) and offers five candidates; every slot rolls a rarity from the Showdown tier (Poké / Great / Ultra / Master Ball at 40 / 30 / 20 / 10 %), so legendaries are rare but never banned. Thin cells are filled with visitors of the same type from nearby generations; two skips, and Start over.
2. Loadout — one set per Pokémon from player-contributed and Smogon analysis sets (over 1,100 sets across ~650 species). Mega Evolution is a set choice.
3. Gauntlet — ten hand-built boss teams climbing from a tutorial band to a final wall; the middle bands are drawn at random per run. Both sides are played by the same search AI with full knowledge of both teams, time-boxed per move, so a slow device plays weaker rather than slower.
4. Results — replays, damage breakdown and MVP, and a score (band points × speed bonus × tier handicap). Signed-in players post it; the server replays the whole run in the simulator before accepting it and keeps each player's best.

The in-game How it works? link tells the same story with the live numbers. Design notes: docs/PRODUCT.md, docs/DIFFICULTY.md, docs/BATTLE_AI.md (what the AI costs the player's machine and how it compares with v1); plan and status: docs/ROADMAP.md, session-handoff.md.

Status

• Live at https://rollmon.gg (Vercel; every push to main deploys; rollmon.vercel.app redirects). The game logic (draft, loadout, campaign, score) is TypeScript under web/; the Python layer under rollmons/ remains the reference implementation and test oracle (make test).
• Players can contribute from inside the game (Contribute: a set for any species, a boss team with the ladder level it fits, or free-text feedback); contributed sets land in rollmons/sets/.
• Measured: a desktop core runs ~220k search iterations per 100 ms budget, an iPhone 16 Pro ~85 % of that; a battle costs about 4 s of one core.
• Next: the screen-by-screen UI rework and draft playtesting (docs/ROADMAP.md); battle-replay text in the page language is explored but not built.

Quick start

make test                      # ruff + pytest for the reference layer (Python 3.11)
cd engine && wasm-pack build --release --target web --out-dir pkg   # engine wasm (rustup + wasm-pack)
cd web && npm install && npm run typecheck && npm test && npm run dev   # game at http://127.0.0.1:8975/dist/index.html

See web/README.md for the scripts (headless-Chrome full-run check, battle sweeps, name checks).

Leaderboard setup (Vercel)

The API is one Vercel function (web/api/) backed by Neon Postgres. It needs two environment variables (a third, FEEDBACK_READ_TOKEN, lets GET /api/feedback be read with a bearer token): DATABASE_URL (in the Vercel dashboard open the project, Storage → Create Database → Neon, free tier, connect it to the project) and SESSION_SECRET (any long random string; it signs the account cookies and keys the sign-up address hashes: openssl rand -base64 48 | vercel env add SESSION_SECRET production). Then redeploy. The tables are created and migrated on first use (deploy/leaderboard.sql documents them). Without the database the API answers 503 and the game hides the board; without the secret accounts are off and scores cannot be posted. Accounts have no email and no password reset; at most 5 can be created per network per day.

Contributing data

The easiest way is the Contribute button in the game. In the repo, boss teams (rollmons/bosses/*.txt, rollmons/pool/<tier>/*.txt) and per-species set overrides (rollmons/sets/*.txt) are plain Showdown export text. Validate with:

.venv/bin/python -m rollmons.validate_submission boss rollmons/pool/advanced/Cynthia.txt
.venv/bin/python -m rollmons.validate_submission set rollmons/sets/abomasnow.txt
cd web && node scripts/check-names.ts      # every species / move / ability known to the engine

See CONTRIBUTING.md.

Credits

• poke-engine (MIT) — the battle search engine.
• Pokémon Showdown and @pkmn (MIT) — simulator, data, replay player.
• foul-play (GPL-3.0) — v1's AI client and the design inspiration; no foul-play code is in this repository (v2's export parser, state mapping and runner were written fresh).
• Pokémon is © Nintendo / Creatures / GAME FREAK. This is a non-commercial fan project.