I attend a small handful of conventions throughout the year and often staff them, running various events for the attendess to enjoy. One of my favorite is Anime Jeopardy. While more of a "web app" as opposed to a traditional webpage, this game was built in PHP using a MySQL database as it's foundation. I run it off a local Apache server on my laptop (so that no Internet access will be required), and it's played using two different pages, with an additional two pages used for maintaining the databse.

The game page is refreshes every half-second, checking for the current status and settings from the database. This is what the audience and contestants see.

The host page is password protected and only visible to the host(s) of the game, and controls the game. When the host clicks on a value-box from the gameboard, it makes a quick change in the database and both pages then see it.

While not used for actual gameplay, the add page is used by the general public to submit questions for use in future games. It's widely advertised on various social media networks, and questions need to be approved by me before they're added to the game.

Lastly is the admin page, for editing existing clues, approving submitted ones, etc. Like the host page, this too is password protected.

I've made a copy of all four pages here if you'd like to play around with them. As a small note, although the game page would normally auto-refresh, I have disabled that for this online backup of it; I wouldn't want someone to accidentally leave it open for a few days.
Game Page - The board the audience sees
Host Page - This is where you run the game. The password is optimus
Add Page - Submit questions to be added to the database
Admin Page - Update and manage the database of questions.