Tic Tac Toe
The first thing we built to learn real-time multiplayer. It still works, so it stays.
01
The Curiosity
Before building anything ambitious with live multiplayer, build the simplest game that needs it and see what breaks.
02
The Build
One Firestore document per game, a listener on each side, a QR code to invite the second player, a win check, a rematch. Everything later games needed was in there in miniature: the lobby, the invite link, the "waiting for the other player" state, and the stats that follow a player around.
03
The Result
Two players, one grid, still online.
04
What We Learned
The lobby, the invite and the rematch turned out to be the reusable part. The game was the excuse. That pattern became a written guide, and every multiplayer project since has started from it.