How PlayAdda works
Most online games send every move to a company's server. PlayAdda works differently: the players' browsers talk to each other directly. That is why the site can stay free with no accounts, and why it works the moment you open a link.
1. A six-letter invite code
When you create a game you get a code like KRT-492. Codes use 30 easy-to-read characters, leaving out look-alikes such as 0 and O or 1 and I, so they are easy to read out on a call. There are over 700 million possible codes.
2. Finding each other
Your browser turns the code into a scrambled room name and announces itself on several free public relay networks at once. Friends who open your link do the same and find you there. The relays only help introduce the browsers; the connection details are encrypted with your room code, and once you are connected the relays are no longer used.
3. A direct connection
Browsers then open a direct WebRTC connection, the same technology video-calling sites use. Public STUN servers help devices behind home routers find a path to each other. On some strict networks a direct path is not possible; if a friend cannot connect, switching one person from mobile data to Wi-Fi usually helps.
4. The host is the referee
The person who created the room is the host. Their browser keeps the official game state, checks every move against the rules and sends the result to everyone with a sequence number, so all screens stay in step. Anyone who joins late or reconnects gets a full copy of the current game.
5. Fair randomness
Before each round every player's browser picks a secret random number and shares only a fingerprint of it. When all fingerprints are in, the numbers are revealed and combined into the seed for dice, tickets and calls. Because each player locks in their part before seeing the others, nobody can steer the result. Every browser re-checks this and shows “verified fair”.
6. Dropping out and coming back
Your seat is remembered on your device. If your connection drops, open the same link again and you are back in your seat. If the host leaves, the next player who joined becomes the host automatically and the game carries on.