INSIDE THE GRID

Tic-Tac-Toe 3D with a TWIST

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INSIDE THE GRID

Inspiration

I wanted to build a Reddit game that feels different from a normal flat board game.

The main idea was simple: take tic-tac-toe, move it inside a glowing 3D cube, and make movement part of the strategy. We liked the idea that the player is not only placing marks, but also traveling through space, trying to outplay an AI rival, and thinking in three dimensions.

I also wanted the game to feel native to Reddit, not just a web game pasted into a post. That is why I focused on Reddit leaderboards, quick play sessions, and a format that works both on mobile and desktop.

What it does

INSIDE THE GRID is a 3D turn-based tactics game played inside a 3x3x3 neon cube.

Your goal is to place 3 X marks in a row before the AI places 3 O marks in a row.

The game has two modes:

Easy

  • You can move up to 3 times on your turn
  • You can move through cells that already have marks
  • You still cannot move onto the AI cell
  • After moving, you place an X in a nearby empty cell

Hard

  • You can move up to 2 times on your turn
  • You can move only through empty cells
  • You cannot move onto the AI cell
  • If you cannot complete a legal turn, you get stuck and the game ends

The game also includes:

  • A rotating cube map mini-view
  • Mode-specific leaderboards
  • A stronger AI in Hard mode
  • A bright neon visual style with a space background
  • Mobile and desktop controls

How I built it

I built the game as a Devvit Web app for Reddit.

Frontend

  • Three.js for the 3D world
  • Custom camera controls for looking around the cube
  • A mini 3D cube map UI
  • Custom shaders, glow styling, and visual polish
  • Responsive layouts for mobile and desktop

Backend

  • Devvit Web
  • Node.js serverless backend
  • Hono
  • tRPC
  • Redis for leaderboard data

Game systems

  • 3D movement rules
  • Easy and Hard mode logic
  • Win detection in a 3D board
  • AI decision-making
  • Reddit-based leaderboard saving
  • Expanded game view from the splash post

Challenges I ran into

One of the biggest challenges was making the game feel clear inside a 3D space.

A normal tic-tac-toe board is easy to read. A glowing 3D cube is much harder. I spent more time improving:

  • camera behavior
  • movement clarity
  • hover targeting
  • mini-map readability
  • mobile UI layout

Another big challenge was game logic.

Because players move before placing marks, the rules are more complex than normal tic-tac-toe. I had to handle:

  • legal movement in two different modes
  • stuck states
  • 3D line checks
  • AI path choices
  • fair result states for both player and AI

We also ran into Reddit-specific challenges, especially around:

  • playtest flow
  • webview sizing
  • desktop vs mobile presentation
  • integrating leaderboards in a clean way

Accomplishments that I'm proud of

I am proud that I turned a simple idea into something that feels like its own game. My first ever game on Reddit! :)

Some of our favorite parts are:

  • A full 3D playable cube instead of a flat board
  • Two modes that create very different strategy
  • A strong Hard mode AI that can attack, defend, and avoid bad paths
  • A mini cube map that helps players understand the board
  • Reddit leaderboard support tied to the game flow
  • A visual style with neon beams, bloom, and a space sky that makes the world feel alive

What I learned

  • designing readable 3D game spaces
  • balancing game rules for short play sessions
  • building UI that works in Reddit webviews
  • adapting layouts for mobile and desktop
  • connecting real-time game feel with backend systems like leaderboards

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