Chat Raid Boss

Your whole Twitch chat becomes one raid party.

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Inspiration

Most chat interactions are polls and predictions: people click once and go back to lurking. MMO raids are the opposite. Everyone has a role, people save each other, and the boss reacts. We wanted to bring that feeling to Twitch chat with nothing to install.

What it does

Chat Raid Boss is an OBS browser-source overlay. When the streamer starts a raid, chat fights a boss together:

  • !atk to hit (subs crit more often), !heal to revive knocked-out raiders, !shield to block the boss's next strike
  • Spamming the same emote builds a combo that deals burst damage
  • Bits deal massive damage
  • Every few seconds the boss knocks out real chatters by name. Others have to heal them back in.
  • The boss enrages at 50% HP and gets desperate at 20%
  • An AI narrator (OpenAI) taunts the top damage dealers in character, based on what's actually happening
  • A HYPE meter fills as chat plays well; at 100% anyone can fire !ult for a massive hit
  • Channel Points (via EventSub) can trigger Smite, Mass Revive, or Freeze the boss
  • Victory or defeat screen with confetti and awards: MVP, Medic, Tank
  • Juice: an SVG boss that changes form each phase, floating damage numbers, particles, screen shake, and synthesized sound effects
  • Extras for creators: an attract-mode demo loop (/attract), a compact corner overlay, a command cheat-sheet overlay, OBS and viewer guides, Twitch panels, shareable result cards with OG images, and press slides with a storyboard.

The streamer sets it up from a studio page:

  • Paste a channel and pick a preset (auto-chosen from live viewer count).
  • Optionally tune HP per raider, cooldowns, and attack speed.
  • Copy one URL into OBS. The overlay is transparent and looks the same at 720p, 1080p, or 1440p.
  • Mods can run it from chat with !raid start and !raid reset.
  • Prefer a smaller footprint? A compact corner widget (layout=compact).
  • Streamer kit: Twitch panel images, a viewer command guide (/commands), an illustrated OBS guide (/obs), and a shareable result card for socials (/r).

How we built it

  • Built with OpenAI Codex in a single thread, from the game design and engine to the Twitch IRC client, UI, and docs.
  • Next.js 15 (App Router) + TypeScript + Tailwind CSS 4
  • Twitch chat over the official IRC WebSocket with an anonymous read-only login, so it works for any channel with no OAuth
  • Twitch Helix API (client credentials) for the channel avatar and live status
  • OpenAI Responses API for the boss narrator, with canned fallbacks so the stream never breaks
  • Twitch EventSub (WebSocket transport) for Channel Points redemptions. Subscriptions are created server-side so tokens never touch the overlay.
  • A pure, deterministic game engine (applyMessages / tick) with an injectable RNG.
    • 19 Vitest unit tests, plus a Playwright smoke test covering the APIs, the studio, overlay transparency, frame rate, the end screen, and console errors.
    • axe-core: 0 violations on 13 pages. Lighthouse on /: 98 / 100 / 100 / 100. Overlay holds 60 fps in both the full and compact layouts.

Challenges we ran into

  • Balance from 5 to 50,000 viewers:
    • Boss HP grows with every new raider, and the boss KOs more raiders as chat grows.
    • Per-user cooldowns stop one spammer from carrying the raid.
  • Chat floods: messages are queued and applied in one batch per animation frame, so 50k messages from 7k chatters process in under 1s.
  • 60 fps at 1080p: profiling showed backdrop-filter was capping the overlay at 17 fps. Removing it brought it to about 60 fps.
  • Never breaking on stream. Every external dependency (AI, Helix, IRC) has a fallback or auto-reconnect.

Accomplishments that we're proud of

  • Zero-setup live mode: paste a channel name and it's reading real chat in about a second.
  • The boss calls out real chatters by name, which gets chat yelling and helping each other.

What we learned

Cooperative mechanics with roles (damage, healer, tank) create much more chat engagement than voting. Short AI lines on a fixed cadence feel alive without spamming the screen.

What's next

  • Twitch Extension version with per-viewer HP panels
  • More EventSub events: raids that bring in "reinforcements," subs as revives
  • More boss packs (9 built-in so far, including seasonal ones), streamer-drawn boss art, plus persistent season leaderboards

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