REPLBAN - Reddit Plays Sokoban

Home screen of Reddit Plays Sokoban
Game instructions and control overview
GamePlay
Mobile Version
Mobile Version
Credits page acknowledging development and contributions
Mobile Version

Inspiration

We were inspired by classic “Twitch Plays” style experiments, where a crowd collectively controls a single game. Sokoban felt like the perfect fit . it’s simple to understand, but deeply strategic. We wanted to explore what happens when hundreds of players must cooperate, vote, and think together to solve a puzzle designed for one brain.

What it does

RPS – Reddit Plays Sokoban is a multiplayer, vote-driven Sokoban experience where Reddit users collectively control the player.

Every few seconds:

Players vote on a move (UP, DOWN, LEFT, RIGHT, UNDO, RESET).
The system calculates the majority vote.
The chosen move is applied to the shared game state.

The entire thread collaborates (or chaos ensues) to push boxes onto goal tiles and win the level together.

Play here: https://www.reddit.com/user/sobojap/
Supported on mobile and desktop browsers only.

How we built it

Backend: Express server running on Devvit.
State Management: Redis for persistent shared game state, tick tracking, and vote counting.
Game Logic: Custom Sokoban engine implemented server-side (movement rules, collision, deadlock detection, win detection).
Multiplayer System:
- Time-based tick system (every few seconds).
- Votes stored per tick in Redis.
- Majority move applied during tick processing.
Frontend Client: GameMaker client fetching state and animating moves based on server responses.

We implemented:

Deadlock detection
Win condition detection
Undo system
Full reset to original map state
Per-user vote tracking to prevent duplicate votes per tick

Challenges we ran into

Synchronizing state between many users in real time.
Preventing users from voting multiple times in a single tick.
Designing a fair and deterministic tick-based voting system.
Implementing undo/reset without corrupting the shared state.
Handling edge cases like deadlocks and invalid moves.
Making sure the backend remained the single source of truth.

Accomplishments that we're proud of

Creating a clean tick-based voting system.
Successfully implementing UNDO and RESET mechanics in a shared environment.
Designing a scalable backend using Redis for real-time shared state.
Turning a traditionally single-player puzzle into a chaotic but cooperative multiplayer experience.

What we learned

Multiplayer state management requires strict server authority.
Even simple games become complex when many users interact simultaneously.
Clear tick timing prevents race conditions and inconsistent state.
Redis is extremely powerful for ephemeral multiplayer state and vote aggregation.
Designing for collaboration means designing for chaos.