Seismic Jenga

Inspiration

Most games on Reddit put you alone in a post. We wanted the opposite: a single thing the whole subreddit builds together, where the tension happens between sessions — the way Reddit actually works. Jenga-style towers are universally readable, and an earthquake nobody controls turns "I placed a block" into "I can't wait to see if it survived."

What it does

Seismic is one shared community tower. You drop a block with your name on it and choose where — a wide beam is a safe platform, a narrow pillar is a gamble worth more points. Lean out over the edge and survive, and you score big.

Then, on a timer nobody controls, an earthquake strikes. The server decides — fairly, for everyone at once — which blocks survive and which come crashing down, floor by floor. You come back to an aftershock report at the top of the thread, a flair on your best climb, and a daily streak pulling you in.

How we built it

Built on Devvit Web with a Phaser 4 webview and a Hono server. Everything that matters is server-authoritative: the tower is a Redis sorted set (atomic appends), credits use atomic counters, and a single pure physics model in shared/model.ts is used by both the client (to preview your risk) and the server (to resolve the quake) — so what you see is exactly what will happen. Quakes fire on a scheduled job with a once-a-minute cron fail-safe, so they happen even with nobody online. All SFX are synthesized in WebAudio — zero audio assets.

Challenges we ran into

• Making the collapse feel right on mobile: a tall tower toppling used to snap the camera and leave a gap. We rebuilt it as a slow camera pan that follows the destruction block by block.
• Keeping it fair and fun: we removed the "first block always wins" problem with a system-owned bedrock, and made centered, safe play score the least so the tower stays lively — reinforced by mini-tremors that lean it over time.
• Reliability: a scheduler hiccup could stall or double-fire quakes. We made the next deadline persist before scheduling, guaranteeing precise-but-never-stuck.

What we learned

Server-authoritative design pays for itself — one shared source of truth for the physics eliminated a whole class of desync bugs and cheating. And on Reddit, the wait is the game: the async loop (place → leave → return to the aftermath) is far stickier than any real-time twitch mechanic.

What's next

Per-subreddit towers with their own leaderboards, seasonal events, and community-built shape packs.

Built With

• css3
• devvit
• devvit-web
• hono
• html5
• javascript
• node.js
• phaser-4
• phaser.js
• reddit
• redis
• typescript
• vite
• webaudio