CrowdProphet

Inspiration

Prediction markets are usually solitary — you're forecasting against a faceless order book. We wanted the opposite: a daily forecasting game where the real opponent is your own subreddit. Every call you make is scored against your community's collective read, not just the market itself.

What it does

CrowdProphet drops six real Polymarket questions onto the subreddit each day, split across two rounds with a two-minute decision clock. Players allocate fake OpenWatch Dollars across YES/NO, then watch a "you vs your sub" reveal showing how their picks stacked up against the rest of their community's calls. Correctly calling against your sub's majority pays a bonus — being right AND contrarian is worth more than just being right. Players build streaks, earn badges (Calibrated, All-In, Conviction, Cold Streak, Contrarian, Longshot Legend), climb both a raw-earnings leaderboard and a calibration-normalized "Sharpest" leaderboard, and can share results straight back into the thread.

How we built it

Built on Reddit's Devvit Web platform: a Hono server backed entirely by Devvit Redis (wagers, leaderboards, streaks, badges, community splits — no external database), real market data pulled from Polymarket's public Gamma API, and a Phaser-driven reveal/results experience layered under a plain HTML wager screen. The whole thing runs as a single evergreen post per subreddit, with scheduled jobs handling the daily market fetch, live price refresh, and settlement sweep.

Challenges we ran into

Getting a real crowd to feel alive on a subreddit with only a handful of active players — we auto-seed a believable baseline split so the "you vs your sub" reveal never looks hollow on day one, while keeping the actual payout bonus gated strictly on real participants so it can't be gamed. We also hit a platform-level domain-approval delay on Reddit's side for our real-market-data source, and had to move fast to satisfy a late-arriving App Review requirement (automated scoring comments must reply to a pinned comment, never post top-level) with only hours left on the clock.

Accomplishments that we're proud of

A genuinely native Reddit game — no external site required — where the core hook (your sub is the opponent) actually shows up in the mechanics, not just the marketing copy: real crowd-relative scoring, a calibration-aware leaderboard that rewards good forecasting over lucky volume, and a full compliance pass completed under serious deadline pressure.

What we learned

How much "the crowd" needs deliberate design to feel real rather than empty — and how tightly Reddit's own review requirements (in-line UI limits, comment-placement rules) shape what a genuinely native game can look like, in ways that push toward better design once you work within them rather than around them.

What's next for CrowdProphet

Full public listing via devvit publish, topic-specific boards (politics, sports, tech) so different communities get markets suited to them, deeper crowd analytics, and continued polish on the calibration-scoring system as more real players build a track record.

Built With

• claude