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Host instructions

Running a Bingo50 session

Everything you need to set up, host, and troubleshoot a Bingo50 game — read this once, then keep it open in a tab during your first session.

Ready to run it?

Opens the host console in a new tab. You'll create the game and get a join QR code from there.

Click here to start the game ↗
01

Setup — before the room fills up

  1. Open the host console (the button above) on the device that's connected to the projector or shared screen. A laptop is easiest — this screen is meant to be seen by the whole room, not held in your hand.
  2. Check you've got a stable internet connection. The console and every player's phone sync live through the same backend, so a dropped connection mid-session will stall things for everyone, not just you.
  3. Decide your number-calling pace before you start — Bingo50 doesn't auto-call numbers on a timer. You control the pace by pressing Spin yourself, so you can go as fast or slow as the room needs.
  4. Have a way to show the QR code big enough to scan from across the room — project the host console screen itself, since the join QR code is built into it.
02

Hosting — running the session

  1. Press Create Game →. This generates the join QR code on screen, along with a unique room code for this session — shown beneath the QR code, in case anyone needs to type the link manually. Each session gets a different room code automatically, so simultaneous games run by other hosts never interfere with yours.
  2. Optional: the first time you use theming, paste your Gemini API key into the field above the theme box and press Use this key for this session. The key stays only in that browser tab's memory — it's never saved to any file, and you'll need to re-enter it next time you open this page in a new tab. Then type a theme into the box beneath it — a company name, or just a vibe like "rainbow unicorns" — and press ✨ Generate Theme. This recolors the game, renames it, and swaps in themed stamps, and applies automatically to every player's phone too, not just your screen. Takes a few seconds. If it fails, you'll see an error with the option to retry or just skip it and keep the default look.
  3. Tell players to scan the code with their phone camera — no app, no login. Each player enters their name and gets a random 5×5 board.
  4. Players have 30 seconds to reshuffle their board if they want a different layout. Watch the player count on screen tick up as people join.
  5. Once everyone's in, press Start Game →. This moves you into the main console: the join QR (still scannable any time), the number-draw panel, the called-numbers list, and a live grid of every player's board.
  6. Press Spin! to draw the next number. It announces on screen and gets added to the called list automatically.
  7. Players stamp the numbers as you call them, on their own phones. You don't need to do anything on their behalf — the live player grid is just for you to watch progress.
  8. When someone gets 5 in a row, they'll typically call it out in the room. Bingo50 doesn't auto-declare a winner — that's a deliberate choice so you can confirm it the way that fits your room. Check their board on the live grid (boards that are one line away are highlighted automatically) before confirming.
  9. To run another round with the same players: press Play Again ↻. To clear called numbers only, without affecting anyone's board or stamps, use Reset Numbers ↺ instead.
03

What players see and do

On their phone
  • Enter their name — that's the entire login step.
  • Get a random 5×5 board, numbers 1–50, with a FREE square in the centre.
  • 30 seconds to reshuffle the board as many times as they like, before it locks automatically.
  • Pick from 5 stamp styles, then tap called numbers on their own board to mark them.
  • Tapping a stamped number again removes the stamp, in case of a mistake.
What they don't need
  • No app download, no account, no password.
  • No need to keep the host console open — that's your screen, not theirs.
  • No need to track other players' progress — that's what your live grid is for.
04

Troubleshooting

A player's board isn't showing up on my live grid
This is almost always a connection issue on their end — ask them to refresh the page and re-enter their name. If it persists, check your own internet connection on the host device, since the sync runs through the same backend for everyone.
Someone joined after I already pressed Start Game
They can still scan the same QR code and join — the join code on the main console screen stays live throughout the session, not just on the front screen. They'll just start with fewer numbers called than everyone else.
Two people are both claiming bingo at the same time
Check both of their boards on the live player grid — both will show as fully highlighted if they've genuinely completed a line. There's no automatic tie-break; that's a judgment call for you as host.
I want to run another round for the same group
Use Play Again ↻. Same room, same QR code still works — players don't need to rescan, they just get a fresh board automatically.
I want to start a brand new session for a different group entirely
Open the host console fresh — go back to the homepage and open Bingo50's instructions again, rather than reusing the same browser tab. Each session gets its own room code in the address bar (the part after ?room=), so a completely new tab guarantees a new, independent room rather than reusing the previous group's. This is also what makes it safe for two different hosts to run Bingo50 for two different groups at the same time — each gets a different room code automatically.
What can the theme generator actually change?
Only three things: the colour palette, the game's name, and a few of the stamp icons. The grid size, numbers 1–50, timer, and how stamping works never change, no matter what's typed into the theme box. Four stamps (tick, fire, star, diamond) always stay in every game too — only some of the remaining slots are themed.
My theme prompt didn't find many relevant stamp icons
That's expected for some prompts — not every company name or theme has obvious matching emoji. The game fills any remaining slots with generic ones rather than forcing an awkward fit, so the stamp set is always complete even if it's not fully themed.
The theme generator failed, or applied on my screen but not players'
Two different things can go wrong, and the error message tells you which: if generation itself fails, nothing changes and you can just press ✨ Generate Theme again. If generation succeeds but syncing to players fails (a connection hiccup right after), your own screen will already show the new theme while players are still on the old look — pressing ✨ Generate Theme again re-syncs it properly. Either way, you can always skip theming entirely and press Start Game → — the default look works exactly the same.
It says my API key wasn't accepted
Re-enter the key in the field above the theme box — it may be mistyped, or it may have been revoked (for example, if it was ever accidentally shared somewhere it shouldn't have been, the right move is always to revoke and generate a fresh one, never keep using a key once you suspect it's been seen by someone else). Get a new key free at aistudio.google.com if needed.
The host console URL doesn't have a password — is that a problem?
Correct, there's currently no login on the host console. Anyone with the direct link to host.html could open it. For an internal corporate or school session this is usually a low risk, but don't post that specific link anywhere public — only share the player join link (the QR code), not the console link.
⚠️ Before a real event: do a full run-through with at least two devices — one acting as host, one as a player — so you've seen the whole flow live at least once before a room full of people is depending on it.