How Quizzy keeps everyone on the same clock

In a quiz, everyone should get the same amount of time for each question. That sounds easy. But every phone gets the question through the internet, and the internet isn’t always quick.

The problem: a message that arrives late

Imagine the quiz host shouts “Go!” to start a race. Everyone hears it at once, except one friend wearing headphones. Someone taps them on the shoulder 10 seconds later. They start running, but the race is nearly over.

A phone on slow or patchy Wi-Fi is like that friend. The host says “Go!” and that phone hears it late, sometimes 20 seconds late. Before, the phone started a full timer when the question finally arrived. The player answered, but the host had already closed the question, so their answer didn’t count. It looked like the game was broken.

Why a phone falls behind

The message isn’t lost. It’s stuck on the way, like a letter sitting in a busy sorting room. Most often the Wi-Fi is weak, or busy because a whole room is sharing it. Sometimes the phone is switching between Wi-Fi and mobile data, which drops the connection for a few seconds. Or the player opened another app, or the screen locked, and the phone paused the game to save battery.

When the connection comes back, all the waiting messages arrive at once. By then, some of them are old news.

The fix: one clock everyone can read

Every message in a Quizzy game passes through our server on its way to the phones, a bit like letters going through a post office. The post office has one clock, and that’s the clock everyone uses.

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   1. Every phone learns the post office’s time

   Every few seconds, each phone sends the post office a tiny “hello”. The post office writes back with the time on its clock. The phone checks how long the reply took. If it came back fast, the phone knows the post office’s time very closely. Slow replies are ignored, because they can’t be trusted.

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   2. The host stamps each question with the time

   When the host sends a question, it writes the post office’s time on it, like a postmark on a letter.

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   3. Each phone checks the stamp

   When the question arrives, the phone looks at the stamp and the clock. If the question was sent 8 seconds ago, the phone knows it’s 8 seconds late, and takes 8 seconds off the timer. Everyone’s timer then runs out at the same moment.

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   4. If the question has already closed

   Sometimes a question arrives after its time has run out. Then the player doesn’t get the answer buttons, because the host can’t count an answer any more. Instead a panel slides up from the bottom of their screen. It says their phone fell behind, and lists why that might be. They can tap Sync to the latest question to jump to where the game is now, or just wait: the next question comes as normal. If they close the panel, Why? opens it again.

Can a player cheat by slowing their internet down?

Some players wonder: if my question arrives late, do I get extra time? Could a friend whisper the answer before my question even shows up? No. Slowing your connection on purpose only makes things worse for you.

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   The timer runs on the post office clock

   A question that arrives 8 seconds late has 8 seconds less on its timer. Waiting longer for it never adds time.

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   The host closes the question, not the phone

   When the host’s time runs out, the question closes for everyone. An answer that arrives after that doesn’t count, whatever the phone’s own screen says.

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   Speed is timed by the host

   Speed points are worked out by the host (in Arcade Mode, by the big screen), from when the question went out to when the answer came back. A phone gets at most a second and a half off for normal internet delay, never more. So a phone that got its question late also scores like a slow answer.

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   Changing the phone’s clock does nothing

   The phone only reads the post office clock. It can’t change the host’s.

So by the time a friend’s whisper helps, the time spent waiting is already gone, and it shows in the score. Slow internet can cost a player time. It never gives them any.