Reddit Tic Tac Toe Showdown

Let's play tic-tac-toe.

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Inspiration

We wanted to build something fun, instantly engaging, and native to Reddit’s social fabric. Tic Tac Toe was the perfect candidate — universally known, quick to play, and with surprising depth in a competitive setting. The idea of instant matches between two Redditors, directly inside a post, felt like a great way to turn Reddit into a game board.

What it does

  • Reddit Tic Tac Toe Showdown lets two users instantly compete in a shared game by simply clicking the board. The first two players to click are matched automatically. A green box shows the current player, red marks the opponent, and the game updates in real-time using Reddit’s shared state. Once a match ends, the board resets and is open for new challengers.

How we built it

  • We used Reddit’s Developer Platform to build a real-time, multiplayer experience using:
  • Shared State to sync the game board across all users (redis)
  • Session awareness to differentiate players
  • HTML/CSS/JS for a lightweight UI
  • No external backend — everything runs within Reddit
  • We kept the board and state logic super lean to ensure instant response and no lag.

Challenges we ran into

  • Player identification: With no direct auth flow, we had to track and separate players with only what Reddit gives us.
  • Race conditions: Ensuring only two users are matched and no interference from others was tricky.
  • Minimal UI: Designing something visually clear with almost no room for customization or assets was a challenge we embraced.

Accomplishments that we're proud of

  • Built a full real-time multiplayer game without any backend
  • Matched players automatically with no input — just click to play
  • Maintained a clean, responsive UI entirely inside Reddit

What we learned

  • How to leverage Reddit's shared state(redis) to build a multiplayer experience
  • Designing for ultra-lightweight interactivity within tight platform - constraints
  • Handling concurrency, input conflicts, and reset logic with no backend server
  • The power of simplicity — a small game with no frills can still be extremely engaging

What's next for Reddit Tic Tac Toe Showdown

  • We're just getting started! Here's what's on the roadmap:
  • Leaderboard to track top players across Reddit
  • Match history with win/loss stats
  • Emoji reactions or chat bubbles for light in-game banter
  • Timed turns to prevent stalling
  • AI opponent when only one user is available
  • Subreddit-specific tournaments
  • Custom skins or themes unlocked by achievements

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